Clint Hurdle is always saying that “today’s game is the biggest of the season.” It’s his way of maintaining that one-game-at-a-time focus.

But today’s game IS the Pirates’ biggest of the season.

They’re reeling, in danger of matching their longest losing streak of the season at the worst possible time. A fifth straight loss would wipe out the last of their five-game lead over the Cubs — all in a matter of five days.

Francisco Liriano needs to pitch up to his ace status. He’s facing Clayton Kershaw in Dodger Stadium. He could be facing Cy Young on the moon. Doesn’t matter. He has to give the Bucs a chance to win this game, for two huge reasons.

One, to stop the skid and all the bad vibes in the wake of Jung Ho Kang’s devastating injury.

Two, to give the Pirates a good chance of taking this series. Liriano takes care of this one, Gerrit Cole figures to take care of Sunday’s game against Mike Bolsinger.

The Cubs called out the Pirates earlier this week, and are in the process of doing the same to the Cardinals this weekend. Time to put your foot down, as Hurdle likes to say.

By the way, for those disappointed with how infrequently I’ve had posts here, given the other time-consuming demands of canvassing the Bucs … from here on out, I’m gonna throw up something at least once a day, usually more. There’s only 15 games left. Time to step up. Something else Hurdle is always saying.

In some ways, the ongoing series in Cincinnati is the Pirates’ most important of the season. Why? Because the Cubs are playing the Cardinals concurrently, meaning every Buccos win means one of two things:

Either they distance themselves from the Cubs for the important, home-field-netting No. 1 Wild Card spot.

Or they get closer to the Cardinals and the even more important division title.

But in Monday’s opener at Great American Ball Park, the Pirates dropped the ball — or booted it, threw it away, whatever view you want to take of the four errors that gave the Reds a 3-1 victory and Anthony DeSclafani his first win in over a month.

In other words, Clint Hurdle may not have picked the best time to give Travis Snider his first start, and Sean Rodriguez his first start of the season at shortstop.

Hurdle has two managerial staples: Following an often long-ago formulated agenda regardless of current circumstances, and “We only have to worry about what we’re doing, not what anyone else is doing.”

Maybe this was a time he should have made an exception, and manage to the circumstances.

Maybe it wasn’t a good time to rest Aramis Ramirez and Starling Marte, after both had homered in Sunday night’s win in St. Louis. Yeah, so did Rodriguez — but that didn’t make him a better shortstop.

Yeah, Hurdle had to deal with the quick turnaround between games — 13 hours from last pitch in St. Louis to first pitch in Cincinnati. But a generally held belief is that travel fatigue usually sets in the day-after, not immediately, so Marte and Ramirez may have been fresher yesterday than will be tonight.

We’ll see.

Let’s assume for a minute that the Pirates will NOT head off the Cardinals for the NL Central title — I know it’s a stretch, but bear with me.

That would mean an inevitable Wild Card game against the Cubs.

How critical does that scenario make the seven remaining regular-season games between the teams? In other words, what is the value of the No. 1 seed and the home-field advantage that comes with it?

Don’t quickly dismiss that with, “Duh! Of course hosting that game is huge.”

But would it be decisive? This currently hypothetical issue is rife with pros and cons.

The Bucs are having a season-long problem with winning in Central cities — 7-18 at this moment; but Jake Arrieta, Joe Maddon’s likely choice for the WC start, has won both starts in PNC Park this season with an 0.64 ERA.

The Pirates might prefer getting Jon Lester, but that would happen only if the game is in Wrigley Field, where the lefty has made 17 of his first 25 starts.

Gerrit Cole, who would get the ball, has been a sharper road pitcher in his young career (2.87 ERA v 3.26) and is 4-1 in five starts in Wrigley, where he has yet to allow a homer in 30 innings — while fanning 40 and walking five. 

The Cubs would have to be taking a lot of momentum into a Wrigley Wild Card game, since they’ve been chasing the Bucs all season … Blackout versus Bleacher Creatures.

Anyway, it’s far from decided. By the way, the schedule still shows only six remaining games between the teams; the seventh will be the makeup of the Aug. 3 rainout at PNC Park. The makeup date hasn’t yet been announced, but it will be during the Cubs’ Sept. 15-17 visit, either on Sept. 14, a scheduled off day for both teams (they’re waiting approval by the MLB Players Association) or as part of a day-night doubleheader on the 15th.

It’s not exactly painting-by-the-numbers, but the Pirates are perfectly sticking to a time-honored formula for becoming a champion:

.500 + .667 = X

Translation: Go .500 on the road, win two-out-of-three at home, get to play untold number of more games in October.

Entering tonight’s opener of a four-game series in Miami, the Bucs are .517 [30-28] on the road — an impressive recovery from an 8-13 start. And they have played .688 [44-20] ball in their PNC Park fortress.

Of course, we still don’t know the value of “X.” Another Wild Card game? Or jump right into the best-of-five National League Division Series as Central champs? … 

Actually, Clint Hurdle does have a problem. He says having too many good players — as he now does with the returns of Josh Harrison and Jordy Mercer — is a blessing, not a problem. He means that from that standpoint of having many choices, none of which would be wrong.

However, the problem is: How do you keep everyone sharp? This is a game that feeds on reps, the key to timing. You can ration playing time, but not rhythm and flow. It will be a challenge. … 

I’ll say it again: Trades of players out of cities that embraced them continue to be a boon to a newspaper industry leaking red from advertising revenue. Chase Utley made his own contribution, taking out appreciative full-page ads in both Philadelphia players following his deal to the Dodgers. … 

Francisco Liriano in his last five starts: 4.67 ERA. His and the Bucs’ records in those starts: 3-0 and 5-0, respectively. File this under “things even out.”

Last season, Liriano had the third worst run support among NL starters at 3.16 runs per game. This season, his 5.26 runs per game is the fifth best. … 

In 2014, the Bucs muscled a total of 62 homers out of PNC Park. They’ve already left the park 59 times this season, with 17 home games remaining. … 

From the pits to the pinnacle, in a three-year flash? These Bucs could very well pull it off.

Could this be the best Pirates team, in terms of wins, of the modern era — for present purposes, “modern” being since Thomas Edison, the Steve Jobs of his time, gave the first demonstration of motion picture with sound, in 1910?

Short answer: Yes.

Longer explanation:

The 1979 World Champs and the 1991 Division Champs both posted 98 victories, the franchise high since the original Naughts — the 1909 and 1903 Bucs won 110 and 103, respectively.

To get to 99, today’s Pirates will have to play .636 ball (28-16) the rest of the way.

Sound tough? Well, they have been playing .652 ball the last three months, going 58-31 since May 9.

Paces tend to lie even more often than some statistics, so it may not happen. But is is a very real possibility — and only three seasons after the end of that losing cycle, a remarkable testament to Bob Nutting, Neal Huntington, Clint Hurdle and a clubhouse-full of players pulling on the same end of the rope.

Pedro Alvarez’s fifth-inning home run — the 1,000th hit at PNC Park, a nice footnote — could do little to avoid a 4-1 loss to the Diamondbacks. Alvarez had a chance to do something more about it in the eighth, when he came up with two outs representing the tying run against Daniel Hudson, a former starting pitcher off whom he owned two homers hit with no one on base early in games.

Alvarez struck out.

Another unfortunate example of why he is possibly the least impactful legitimate slugger in the Majors. 

The Pirates, obviously, accept Alvarez at first base because — other than the occasional truly impressive defensive play — of the threat of his power, both in how it affects opposition strategy and in terms of delivery. The former seems to happen more than the latter.

Sixteen of his 19 homers have been solos, putting a dent into his overall solid offensive line. His 59 RBIs are second on the Bucs and already three more than he had all last season. Subtracting himself, however, he has driven in 40 teammates — of the 149 who have been in scoring position when he has come up.

Team RBI leader Andrew McCutchen, for comparison, has delivered 59 teammates (77 RBIs less his 18 homers) in fewer chances — 144 have been in scoring position for him.

Alvarez’s .252 average would be a full-season career best for him. But he is that rare Major Leaguer whose average is lower (.235) with men in scoring position. Because of various factors — pressure on pitcher, defensive alignments, etc. — the league norm is higher with MISP (.257) than not (.246).

The Pirates, evidently, have finally come full circle.

The Mets anticipated and built up this series with the Bucs as their “big weekend,” and the Citi Field crowds will reflect that drumroll. Having spurted to the top of the National League East at the expense of second-rate competition, the Mets regarded the Pirates as a test of whether they are for real.

Not too long ago, a “big weekend” against the Pirates meant something totally different: Teams looked forward to playing them so they could fatten up with some easy wins.

Now the Bucs are proving grounds? This scenario is so reminiscent of what veteran Buccos like Andrew McCutchen and Neil Walker started saying in 2012, when the turnaround had its dress rehearsal: “We’re no longer the team other teams look forward to playing.”

Another take on that: Going from being the hunter to being the hunted.

So now it’s open season on Pirates?

What a world. …

And congratulations on Clint Hurdle’s 400th Pirates win, nailed Friday night.

To me, the most significant thing about the “milestone” are the wins by the managers between Hurdle and the last member of the Pittsburgh 400, Jim Leyland, who managed his last Buccos game two decades ago:

• Gene Lamont: 295
• Lloyd McClendon: 336
• Jim Tracy: 135
• John Russell: 186.

Hurdle had a lot of help, obviously, but he fixed it. 

When the Pirates were going through that mid-June run of fabulous pitching — 8 wins with three-runs-or-fewer in a span of 11 games — we kept saying that when the arms inevitably falter, it will be up to the bats to do the heavy-lifting.

Remember?

Well, it’s happening now.

The Bucs have won three straight home games while allowing four-plus runs. That doesn’t happen often in PNC Park, a pitchers’ stronghold. The last time the Pirates did this was on Aug. 28-30, 2006, when they outscored the Cubs 28-21 during a three-game sweep. …

Speaking of sweeps, the Bucs will be going for their 11th of the season in today’s series finale with the Dodgers. The last time they had as many was, of course, in 1992, with 12; and they had 13 series sweeps in 1991. … 

And speaking of things balancing out: Pirates reliever have picked up 10 of the team’s 17 wins since July 6; up to that point, with the starters having dominated, the bullpen had a total of nine of the Bucs’ 47 wins. … 

With Friday night’s win in 10 innings over L.A., the Pirates remarkably evened their record in extra inning games at 7-7. Why remarkable? They lost their first six overtime affairs. … 

Similarly, that win improved their walk-off record to 7-8; the Bucs had lost their first eight walk-off affairs. … 

“Timing is everything.” We always hear that. Last week, the Pirates unwittingly gave us a demonstration of it.

Left-hander J.A. Happ is starting tonight against the Cubs, making his debut for the Bucs. There is little doubt that the guy taking the mound at PNC Park instead would have been Vance Worley — if only A.J. Burnett’s right elbow had throbbed a day earlier.

• On Wednesday, the Bucs traded for Joe Blanton.
• Thursday afternoon, Blanton reported to Cincinnati and Worley was designated for assignment to open up a roster spot for him.
• Thursday night, Burnett painfully faced the Reds.
• Friday morning, Burnett went on the 15-day disabled list with elbow inflammation.
• Friday afternoon, the Pirates, in the words of GM Neal Huntington “directly influenced by Burnett’s injury,” dealt for Happ hours before the Trade Deadline — and paid a pretty hefty price in Adrian Sampson, who had carried over a solid Spring Training showing with the Bucs into a solid Triple-A campaign at Indianapolis.

MILWAUKEE — As always, there are a lot of uncertainties approaching MLB’s annual July 31 Non-Waiver Trade Deadline. But here is one definite: The Pirates are in the process of making the hard decision of whether they need an upgrade at first base for the stretch.

“Our general manager knows as well as I do what we look to identify as strengths and weaknesses on our club,” manager Clint Hurdle said prior to Saturday night’s game here. “I don’t know what will happen two weeks down the road. Could it be different? Yeah, it could be. Could it be the same? It could be.

“I’m not a fan of saying, ‘We need A,B and C, when A,B and C is out there (in the clubhouse). So I’m not gonna bang the drum for somebody when I’ve got a team full of players out there. We will do everything we can to fortify and make our club better.”

This is an extremely sensitive issue, particularly for a manager who recognizes and appreciates Pedro Alvarez’s work ethic and commitment, which started with him buying into changing positions from third to first.

Alvarez’s 15th error of the season, letting a grounder through his legs to set up a two-run seventh inning Friday night, was another game changer. Regularly removed for defensive purposes late in even tied games, Alvarez’s 15 errors, most of routine plays, have come in 575 innings. The Reds’ Joey Votto is second among National League first basemen with five errors, in 738 innings.

Overall, Pittsburgh first basemen have combined for 18 errors. The other 14 National League teams average four errors at the position.

Alvarez also stands out as the only lefty-hitting power threat in the Bucs’ lineup, and took 12 homers and 41 RBIs into Saturday night’s game.

Ironically, Hurdle brought up the name of a ‘60s era Buccos first baseman known as Dr. Strangeglove for his fielding misadventures.

“Dick Stuart said, ‘Long as you drive in more than you let in, you get to play.’ I always liked that concept,” Hurdle said. “Play determines playing time — they all know that. We’ve become a team predicated on defense — they all know that as well.

“Players know the game. There’s no sense sending a message ahead of time. Wanting something and getting someone at that position are two different ends of the spectrum. So to bring it up and then not be able to deliver … I don’t know what good that does, either.

“I’m a big fan of doing the best you can with what you got and where you are — until that changes.”