Brett Cecil St. Louis CardinalsZach Gifford | THE INTREPID STL

photo by @cardinalsgifs

This past weekend, I had the chance to attend the St. Louis Cardinals Blogger game, which featured a Q&A session with General Manager John Mozeliak. The Brett Cecil topic came up, and John Mozeliak expressed concern about his performance and his velocity, which is still down about one mph across the board and is the continuation of a four year trend since Cecil moved to the bullpen full time.

Mozeliak’s comments prompted me to ask about Cecil’s spin rates, specifically on his fastballs and curveball, which have dropped about 150 to 200 rpm since last year. There’s some research which suggests decreases in spin rate might be a leading indicator of pitcher injuries, and I’ve already looked at Cecil’s spin and wondered whether he’s really healthy.

As for health, Mozeliak told us that Brett Cecil “says he’s not hurt, which at some point all you can do is trust the player.” He did, however, suggest the issue might be mechanical, specifically arm extension and release point. Luckily for me, release extension data is available. I’m focusing my analysis on his fourseamer, but the same patterns from the charts below hold true to varying degrees across his sinker, cutter, and curveball.

Brett Cecil St. Louis CardinalsZach Gifford | THE INTREPID STL

Sure enough, Brett Cecil is getting less arm extension. Alternatively, he’s releasing the ball farther from home plate. This negatively impacts his effective pitch velocity: the closer he releases the ball to home plate, the harder it looks to the batter.

Brett Cecil St. Louis CardinalsZach Gifford | THE INTREPID STL

Over the last three years, the relationship between Cecil’s release extension and effective velocity is fairly strong. While he’s generally had an effective velocity lower than his release velocity, the difference this year is even more staggering. Separating 2017 from 2015 and 2016, the picture looks like this:

Brett Cecil St. Louis CardinalsZach Gifford | THE INTREPID STL

The majority of points in the lower left corner are from 2017. These are the pitches that have the largest negative effective velocity differential. On average in 2017, his pitches look about 2 mph slower than they’re actually thrown. They’re also the pitches that have the slowest release velocity. On average, he’s releasing his pitches 1 mph slower than the last two seasons. Not good.

Next, I wanted to see how release extension impacts spin rate. I have some concerns about the reliability of spin rate data in 2015, so I’m excluding that year (although Cecil’s fastball spin rates were all better then than they are now). That still leaves us with two years of spin rate vs. release extension data for Brett Cecil, which includes periods where he’s been terrible and periods he’s been dominant.

For a pitcher who uses his fastball primarily up in the zone, a higher spin rate is important to keep the pitch elevated to generate whiffs, flyouts, and popouts. When his spin rate is above 2150 rpm, hitters have managed a lowly .271 wOBA against his fourseamer. When the spin drops below 2150 rpm, hitters own a .397 wOBA. Higher spin generally means more deception, too, which makes it harder for hitters to differentiate between pitches. A spin difference on one pitch likely flows through the entire repertoire.

St. Louis Cardinals Brett CecilZach Gifford | THE INTREPID STL

It turns out, the farther Brett Cecil extends, the more spin he generates. This relationship isn’t terribly strong, but it bears some significance. Less spin means less movement, and Cecil is getting less rise and less horizontal break on his fourseamer, sinker, and cutter. He’s getting less drop on his curveball despite lower velocity, and the pitch is actually “backing up” on him more than ever.

So Brett Cecil currently has a mechanics problem. He’s not getting the same arm extension that he used to. It’s directly impacting the quality of his repertoire, making him easier for batters to read and hit.

Is there an in-season fix? According to Mozeliak, this extension issue is “definitely something that can be fixed in-season, especially if you have someone who’s focused on it.”

Clearly, the team believes it has identified what is holding Brett Cecil back right now and believes they can get him right. To see if they’ve made any progress, I graphed Cecil’s average release extension by game and included a 5-game moving average to get a picture of any trends.

Brett Cecil St. Louis CardinalsZach Gifford | THE INTREPID STL

It looks like the team identified the problem and starting working toward a solution around game 14, which was on April 30th. I hoped we’d see a significant increase in release extension last night (June 13th) after Brett Cecil had six days off, but instead we saw his shortest extension point since May 25th. It’s hard to know how much variation to attribute to park factors (Cecil’s release extension at home is about two inches less than on the road), but at least the overall trend over the past month and a half is in the right direction.

Unfortunately, it hasn’t yet made a difference performance-wise. Brett Cecil had a 4.50 ERA and 3.71 FIP through April 30th, but has a 5.68 ERA and 5.32 FIP since. His K-BB% is nearly identical (13.3% vs. 13.6%), so his xFIP only moved from 4.35 to 4.33.

Hopefully these struggles are just a sign of an adjustment period while Cecil tries to get comfortable again. He strung together seven scoreless appearances from May 19th to June 4th, and looked good again last night over two scoreless innings. The Cardinals need him to lock in soon and help secure the back end of the bullpen.