Has Jimmy Nelson Really Emerged Or Is A Regression Coming Soon?

by Eric Stashin (aka The Rotoprofessor)

Jimmy Nelson has been a great story at the start of 2017, apparently giving the Brewers an ace atop their pitching staff.  Can he continue producing these types of numbers, though:

70.1 Innings
3.45 ERA
1.27 WHIP
71 Strikeouts (9.09 K/9)
17 Walks (2.18 BB/9)
47.7% Groundball Rate
.332 BABIP

He’s showing the entire skillset that we look for, but what has changed from last season to this season?  The biggest alteration has been utilizing his sinker less and his fourseam fastball more:

Last season opponents hit .320 against his sinker, so the change makes sense.  However that doesn’t explain his spike in strikeouts, as he owns a career 7.54 K/9…  Or does it?  His Whiff% on his fourseam fastball has been on the rise, after a 9.60% mark in April, as he was at 13.89% in May and has opened June with a 20.41%.  With the ability to get swings and misses from both his slider and curveball as well, the improvement is an important one.

The other big change has been his control, as he owns a career 3.41 BB/9.  It’s possible that the increased usage of his fourseam fastball has also helped in this regard, considering 54 of his 86 walks last season came courtesy of his sinker (and 8 of his 17 this season).  Throwing that pitch less is going to mean fewer walks, as has happened thus far.

Throw in an inflated BABIP, which has come courtesy of a 20.6% line drive rate, and a still solid groundball rate (47.7%) despite throwing fewer sinkers, and it all comes together for a strong outlook.  He clearly has the ability, the question is going to be if he can maintain this type of swing and miss stuff from his fourseam fastball.  If that happens remains to be seen, but at this point there’s reason to believe.

Sources – Fangraphs, Brooks Baseball, Baseball Reference

Make sure to check out all of our updated rankings: