Ryan Dempster has gotten off to the worst start of his Cubs career. It’s led to some wondering what is wrong or whether or not he’s done. If we look at his ERA it’s gone from 2.96 in 2008 to 3.65, 3.85 and now 7.63. Obviously something isn’t right. We see a similar trend with his FIP (3.41, 3.87, 3.99 and 5.71). Once again, one of them is not like the others.
However, if we dig a little deeper we see the reason why. His HR/FB is sitting at 22.2% right now. Pitchers don’t have a skill here. The true talent skill for Major League pitchers is right around 10%. Dempster’s HR/FB rate from 2008 through 2010 was right about 10%. The unusually high HR/FB rate has resulted in only 59.3% of the runners on base being stranded. So far, you get on against Dempster, you’ve got a good chance of scoring.
xFIP adjusts HR/FB rate to 10% and we see that Dempster’s xFIP since 2008 has been 3.69, 3.76, 3.74 and 3.69 in 2011. He’s been as consistent as possible. His 2008 season resulted in a low ERA and lower FIP because he had a lower than average HR/FB rate. It was about average in 2009 and 2010 and way above average this year. The end result is that he’s basically been the same pitcher aside from home runs all four seasons.
Dempster’s BABIP is also unusually high. It’s .324 this year and it was .280, .302, and .294 in 2008, 2009 and 2010 respectively. Well maybe his line drive rate is through the roof like Matt Garza. Nope. It’s 17.5%, which is just a bit under what he’s averaged since returning to the rotation in 2008. Even stranger, he’s given up a few more fly balls this season and flies have a lower BABIP than grounders do. Also odd, 11.1% of the balls of the bat have been infield fly balls. It had been just under 7% in 2008 and 2010 and at 12.5% in 2009. Balls are just falling in for hits against Dempster and then he’s giving up a ton of home runs.
His control is the best it’s been since returning to the rotation. In 2008 his walks per plate appearances (minus IBB plus HBP) was .098. It was .089 in 2009, .109 last year and .085 this year. 8.5% of the batters he’s faced have reached base via unintentional walk or hit by pitch. That’s it. His strikeouts per plate appearances hasn’t dropped off either. It was .219 in 2008, .205 in 2009, .228 last year when he strukout a lot of batters and back to .206 this season.
The big difference? In 2008 1.6% of plate appearances against Dempster resulted in a home run. It was 2.6% the next season and 2.7% last season. It’s 5.7% this year.
If you give up as many home runs as Dempster has it’s difficult to say he hasn’t been hit hard, but when you look at the line drive rate that’s exactly what we find. Home runs still count of course and he’s given up a ridiculous amount of them. He has not had a good season so far, but there’s no reason from what I can see to think he won’t return to what he’s done the last 3 years. Everything seems to point to him being the same pitcher and he just happens to be rather unfortunate right now in that so many fly balls are leaving the ballpark.