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Studying J.A. Happ Before His Next Start

We know a lot about this particular Astros rotation. We know what Brett Myers is and why he struggles when he does. We know what Wandy is, both at home and on the road. We are coming to grips with what Bud Norris has transformed into this season.

The one wildcard so far (besides the rook) has been the big league piece to the Roy Oswalt trade. I've already looked at J.A. Happ from a Pitch F/X profile last season, and I'm not sure we have enough for that to be effective right now. I did want to dive into his numbers a bit to see why he might be so maddening and what we can learn from him going forward.

Let's start with the big picture. Happ has his highest ERA of his major league career at 5.03. He's 3-5 in nine starts over 52 2/3 innings. That means he's averaging just under six innings per start. It's hard to tell, because he spent time in the bullpen in both 2008 and 2009, but Happ has raised that average quite a bit this season. He's pitching deeper into games, which you would expect from a guy getting a good shot at sticking in the rotation.

Happ's K/9 rate has dipped from previous seasons, but not significantly. His BB/9 rate is lower than last season, but it's right in line with his starts in Houston and his numbers from 2008. He's giving up more home runs than you'd like, and has a batting average on balls in play of .292, which is higher than his career averages, but still lower than is usually sustainable.

That's a big reason why is ERA is up and why both his FIP, xFIP and tERA are at career levels. But, just because his numbers are up doesn't mean he's been at his worst this season. Sure, he's been maddeningly inconsistent. Sure, he doesn't throw hard enough to strike out a ton of batters. Isn't there some hope in there?

I don't know about hope, but I can show you what's changed this season.

First of all, Happ is giving up about 10 percent more fly balls than he has in the past. His line drive rate is also up from seasons past, which means he's at a career low in ground ball rate. That accounts for the spike in his HR/9 rate and why his HR/FB rate is also higher. He's just seeing more fly balls than in the past. That should also settle some of his other problems, because (as clack pointed out the other day), fly balls don't fall for hits as often as ground balls. So, it stands to reason if those numbers hold up, Happ should see declines in his homer rate and WHIP before the end of the season.

That's also assuming he's meaning to generate so many fly balls. Last season, in his time in Houston, his ground ball rate was around 40 percent. Now, it's 27 percent. What if that's not because Happ is trying to generate fly balls, but because of the pitches he's throwing?

Happ's fastball has dropped in velocity from last season. He was sitting at 89.8 for the 2010 season with his four-seamer and 90.0 in his short time in Houston. That's a drop of a full MPH, which should lead to more ineffectiveness. However, he's also throwing the fastball less and had similar velocity readings in 2008, so we may just be seeing some random variation in a pretty secure pattern.

Happ's fastball has always been his best pitch, partly because he locates it well. The biggest change in his pitch selection this season has been the reliance on his curve over his changeup and slider.  Those three pitches are now thrown about the same number of times, which hasn't been true in years past. That jump in curves thrown may also explain why the fly ball rate has spiked.

Looking at straight pitch values through FanGraphs, Happ's curve is still below average, but it's at its highest value in his career. Arnsberg has almost made it into a league-average pitch, which helps considering his slider has taken a nose dive in value. The real benefit here has shown in his changeup, which is about as effective as it was in 2009, but when weighted per pitch thrown, it's been used much more effectively than back then. If Happ needs to fix something, it's getting his slider back to form.

Still, having two effective pitches and one league-average one doesn't explain why Happ has struggled so badly. At least, until we look at his batting profile. Batters are swinging at a career-low percentage of pitches outside the zone. We know Happ relies on that high fastball to be effective, so putting two and two together, it's easy to see why the fastball has lost effectiveness...batters aren't swinging at it any more.

His swing rate in the zone is about the same as usual, as is his outside the zone contact rate. There has been a jump in the zone contact rate, most likely due to batters waiting on that slider or another pitch to flash there instead of being up or in the dirt. That's led also to a slightly depressed swinging strike rate, which also explains his drop in K/9 rate.

Let's summarize what we know about Happ: his fastball is still good, but batters are not swinging as often at it up in the zone, leading to more walks. He's using his change and curve more effectively, but his slider is hurting him. He's also giving up a ton of fly balls and not generating nearly enough grounders, but those fly balls may start finding outfielder gloves soon. He's also been trending towards more effectiveness since April, so we may very well see a good start out of Happ tonight, if he's getting swing-throughs on the change and he gets a few more ground balls and a few less line drives.