Posted by Michael Street on Tuesday, September 15, 2009 at 11:04 pm

In July, I wondered in this column whether Matsui might be heating up and helping the Yanks to climb atop the AL East. Matsui kindly obliged by ripping it up in August, though whether he actually helped his team all that much in the process is open to debate.

In that earlier article, I was focusing largely on Matsui’s hot start in early July, and he swooned a bit after the All-Star break, finishing the month with a .234/.345/.362 line.

It looked like Matsui might return to his career form, in which June (.297/.387/.507) and July (.320/.385/.572) are his strongest months, while August (.279/.347/.471) and September/October (.296/.382/.455) are his second- and third-worst months. (A slow starter, Matsui has the most trouble in March/April, when he typically hits .271/.369/.425.)

What those final two months of the season show more than anything is his diminishing power as the year progresses. 2009’s trend seemed to be slipping into that mold, as he logged SLGs of .492, .483, and .407 through June.

July saw the beginning of his monthly turnaround, as he hit .293/.407/.560 with 5 HR and 19 RBI, both monthly highs in 2009. And then the calendar turned to August.

In 24 games last month, Matsui racked up a .281/.333/.584 line, with 8 HRs and 25 RBI. The Yanks also had their best month of 2009, winning 21 of 28 games and going from 1.5 games ahead of the Red Sox to 6.5 games up, with the division all but salted away.

But are the two connected?

While the fans voted him the Pepsi Clutch Performer of the Month, the BDD writers didn’t find Matsui worthy of distinction in our August Player of the Month awards—nobody (myself included) even gave him a vote.

Some could argue that the difference lies in the notion of “clutch,” which assumes not only that fans who participate in online polls are rational actors, but also that they’re capable of grasping and calculating “clutch” (itself a dubious metric).

Even if we grant that, can we say that Matsui had a “clutch” month, and that he’s the reason the Yanks surged into the AL East catbird seat? Let’s look at some numbers.

Fangraphs will tell you that, in the month of August, Matsui had a “Clutch” rating of -0.37. Without getting into statistical arcana here, the top”Clutch” performer was Rajai Davis, with a Clutch rating of 1.01. (Our BDD Player of the Month consensus pick, Kendry Morales, had a Clutch rating of -.07. Clearly, we don’t care about Clutch, or at least the way Fangraphs measures it, either).

If you want to look at Win Probability Added, Matsui doesn’t score highly here, either. His -0.04 WPA means that he not only didn’t help the Yanks win, he helped them lose. Really?

Let’s look at Matsui’s most productive stretch of August, the nine games he played between the 13th and the 26th. That was the stretch when he produced three two-HR games, three straight two-hit games, and an overall line of .350/.381/.825, with 6 HRs and 18 RBI, the lion’s share of his production for the month.

How helpful was Matsui to the Yanks, who went 7-2 over those nine games?

Gozilla’s first big game was the August 13 drubbing of the Mariners. Thanks in part to Matsui’s 4-5, 2 HR, 5 RBI onslaught, the Yanks won, 11-1. His first homer came in the third, a 2-run jack that lifted the Yanks from being ahead 3-0 to being ahead 5-0, and lifting their win probability from 83% to 90%.

His RBI single in the seventh pushed the score to 7-1 and the win probability from 98% to 99%. His second dinger, in the eighth, made the score 11-1 and didn’t shift the 100% win probability a bit. His big night only helped his team 8% closer to the win, at least according to that metric.

His next big game came on August 21, with the slugfest against the Red Sox, when Matsui also hit 2 homers, though they were his only hits in 6 ABs, producing 7 RBI regardless. The first one, however, came in the fifth inning, a 3-run shot that changed the score from 6-1 to 9-1, and the win probability from 96-98%. His RBI groundout in the 7th and his second 3-run jack changed the score to 16-7 and 19-7, respectively, and didn’t budge the 100% win probability. 2% doesn’t seem like much, when you compare it to all that production.

His last 2-HR night came in a much closer contest, on August 23, though this time his two longballs could only muster 2 lonely RBI. The first came leading off the second inning, giving the Yanks a 2-0 lead and a 9% increase in win probability, and the second homer pushed the lead to 8-4 in the eighth inning, giving the Yanks a 95% win probability, from 90%. A 14% improvement in win percentage, better than his last two games combined.

Yet by contrast, A-Rod’s 2-run shot in the fifth made the score 7-3, and lifted the win probability from 71% to 87%, more than both Matsui’s home runs combined. With such a relatively small contribution to his team’s success, it’s easy to see how Matsui’s 3-13 with 2 BBs in New York’s 7 losses might drag this down.

This might all sound like an argument against win probability or other measurements of leverage or clutch, but what it does show is that Matsui had a very good month amid a great month by his fellow pinstripers. The Yanks had their best month of the season, too, hitting .296/.351/.507, with a whopping 49 HRs and 172 RBI, all season highs.

They likely would have won all three contests without his heroics. His 2-5, 3 RBI performance the next game would come in a 10-9 loss, while his 2-4, 1 R, 0 RBI night on August 26 weren’t really needed in a 9-2 washout.

But let’s not let this take away from Matsui’s great month, which shows he’s healthy enough to DH—a distinction that perhaps damns him with faint praise—and ready for the postseason.

He’s stinging the ball this season, with a 19.6 LD% that’s his best since his 2003 rookie year, and hitting more fly balls, as his 41.5 FB% is his best since 2006. And more of those flies are turning into home runs, at a 16.7% rate that’s the best in his MLB career.

Moreover, he doesn’t appear to be a beneficiary of New Yankee Stadium, at least as far as HR distance goes, though whether the alleged jetstream is helping him may be harder to measure. He’s hitting the ball harder, lifting it more, and is making a good case for the Yanks—or some other team—to find a place for him in 2010.

Because even if the Yankees don’t always need this kind of production, there are plenty of other teams that do.