While I was writing in the offseason about various Mets pitchers, I came across one thing that seemed pretty much true with everyone I wrote about.  The Mets bullpen had huge issues last season.  One of the biggest issues had to do with platoon splits.  Most pitchers had no trouble getting same handed batters out but had major problems getting the opposite handed hitter out on a daily basis. 

As we all know, Lefty pitchers are generally better against lefty hitters and righty pitchers are better against righty hitters.  The changeup is an extremely useful weapon against batters that are opposite handed (lefty pitcher vs. righty hitter or righty pitcher vs. lefty hitter).  The majority of Mets bullpen members last season either threw very few changeups or their changeups were nonexistent at all.

I wanted to take a look at this on a larger scale so what I did was go to Fangraphs and selected 15 pitchers that threw the most changeups and 15 pitchers that threw the least amount of changeups.  Before conducting this study I felt the pitchers with the least amount of changeups would have the biggest platoon splits and pitchers that threw a lot of changeups would have smaller splits.  Here’s a table of the 15 pitchers with the least amount of changeups in 2008.  I used 2008 data and a min of 100 innings pitched (I wanted to make sure they faced a lot of batters).  Also, there were some pitchers on this list that threw Split-Finger fastballs…….they serve the same purpose as the changeup and thus I eliminated from the chart.

The typical OPS platoon split is about 50 points.  Looking at the above table, we see 9 of the 15 pitchers have extreme splits (difference of 80 or more points).  The main culprit is no other than Oliver Perez who had a massive split of 270 points.  Aside from Ollie, we see 5 other guys that had split differences of 140 points or more.  This table clearly shows that a lack of changeup definitely hurts when trying to get opposite batters out.

There were two guys on the above table that had reverse splits, Tim Wakefield and John Lackey.  Wakefield is a bit of an abnormal case considering he throws nearly 80% knuckleballs.  As far as John Lackey goes, he throws a lot of curveballs which are generally effective against both side of batters.  Towards the bottom you see pitchers like Roy Halladay and Roy Oswalt who are just good against anybody.

Now let’s take a look at the 15 pitchers who threw the most changeups during the 2008 season.

The first thing that jumps out to me is that 6 of the 15 pitchers that threw the most changeups are left handed.  This makes sense.  The changeup is effective against opposite handed batters and there are a lot more right handed batters then left handed batters.  This makes the changeup essential for the left handed pitcher.

Here we see the difference between throwing a changeup and not throwing one.  5 out of the top 15 have reverse splits.  They are more effective against opposite handed batters compared to same handed batters.  Furthermore, 8 of the 15 have normal splits.

Only two of the top 15 changeup throwing pitchers (Odalis Perez and Carlos Silva) have extreme splits.  I didn’t really see anything as to why they would have extreme splits.  Perez career OPS split was only 15 points so maybe 2008 was a nominally.  Silva actually has reverse splits of 119 points.

CONCLUSION

I don’t think there’s any doubt that throwing changeups will help combat opposite handed batters.  That being said, I’m not a pitching coach and I’ve heard learning the changeup is probably the toughest pitch in baseball to learn.  Another thing that I learned from pitch FX articles I’ve done is that a changeup is most effective when there is a large differential in velocity between the pitchers fastball and changeup.  The average is somewhere around 10 mph difference, the best have larger differences.  Also, changeups are more effective with a lot of sinking movement or a lot of rising movement.  Any changeup close to (0,0) gets crushed.  So while it’s easy to say pitcher X needs to be throwing more changeups, there’s a lot more that goes into it.