St. Louis Cardinals: A Look at Kevin Siegrist’s Development

Kevin Siegrist has inserted himself as one of the St. Louis Cardinals most depended-upon relievers since debuting in 2013, but he is not without significant and troublesome weaknesses.

At a glance, Kevin Siegrist looked like one of the St. Louis Cardinals’ most dependable relievers in 2016. He was third in innings pitched among Cardinals relievers with 61.2 and fifth with a 2.77 ERA. Manager Mike Matheny relied upon Siegrist late in games and, for the most part, Siegrist delivered.

However, Siegrist’s success in 2016 was supported by unrepeatable luck. He registered a .221 BABIP against, which ranked fifth lowest among 135 qualified relievers. Additionally, his 89.1% strand rate (LOB%) ranked fifth highest among the same set of relievers. The result was a FIP of 4.43, which was 1.66 runs above his ERA.

If either (or, most likely, both) of these rates regress to even average rates without noticeable improvement in Siegrist’s peripherals, the reliever will likely have a much worse season in 2017. There are obvious reasons for Siegrist’s struggles this past year, namely a depressed strikeout rate and declining fastball velocity. However, I will focus for much of this post on his positive development.

For Kevin Siegrist’s career, he has allowed reverse splits against opposing hitters. This means that left-handed batters (LHH) have hit him better than right-handed hitters (RHH) even though Siegrist throws left-handed. This is the opposite of traditional expectations, and is often attributed to Siegrist featuring a change-up as his second best pitch while being without a quality breaking ball.

Siegrist has allowed reverse-splits in every season since 2014. The difference was most drastic in 2015, Siegrist’s best full season, when lefties hit for a .356 wOBA against Siegrist compared to only .227 from RHH. However, Siegrist has improved his overall line against LHH every season since 2014, dropping his wOBA against LHH from .373 in 2014 to .302 in 2016.

I decided to investigate how Siegrist is adapting to combat his reverse-split problem to become a more dependable reliever. As it turns out, the first pitch is the most important for Siegrist against LHH. However, he has had annual trouble locating his fastball to execute his strategy against LHH. Additionally, Siegrist recently modified his curveball, the off-speed pitch he primarily features against lefties.

Following this information, I walk through each of these facets of Siegrist’s attack, analyzing his overall development and comparing his strategy and results versus LHH and RHH.