Four Reasons to Be Optimistic About Oakland’s Sean Manaea

Oakland A’s fans didn’t have many reasons to be optimistic in 2016. The team’s playoff odds peaked at 20%… on April 3rd. As the season wore on, Sonny Gray’s ERA rose almost as high as the home runs against him flew. The team’s 69-93 final record was the icing on the cake.

Sean Manaea provided one bright spot. Acquired from Kansas City in 2015 in exchange for Ben Zobrist, Manaea is a 6-foot-5, 245-pound lefty. He debuted in April and, after tweaking his changeup grip, remained in the rotation the entire season. He gave up more than his fair share of home runs, but the 14.7-point difference between his strikeout and walk rates (K-BB%) proved he could fool batters. His 93 xFIP- ranked alongside that of Rookie of the Year Michael Fulmer.

The 2017 season doesn’t look much rosier for the A’s organization. Our Depth Charts projections have them bringing up the rear in the AL West again. But at least the team’s fans can be optimistic Manaea will perform well in 2017, for four very good reasons.

1. An Excellent Swinging-Strike Rate

When batters swung at a pitch from Manaea, they missed 11.8% of the time. This rate ranks Manaea at the 91st percentile among starters who faced at least 100 batters last year:

Manaea’s peers by this measure are Justin Verlander, David Price, and James Paxton: good pitchers, all.

What does that mean for 2017? Good things, probably. Swinging-strike rate correlates very well year-to-year (r = 0.69), as the following graph shows:

This suggests one can expect Manaea to produce a similar swinging-strike rate in 2017. Swinging strikes leads to strikeouts. Strikeouts are almost always positive.

2. A Very Good Walk Rate

Manaea’s walk rate isn’t as good as his swinging-strike rate, but at 6.2% (75th percentile), it also holds up well relative to other starters. His peers by this measure:

Kevin Gausman is a good comp, as are Matt Harvey and Max Scherzer.

What’s in store for next year? Walk rate correlates moderately well (r = 0.56) year-to-year:

The lower correlation coefficient means we’re less certain about this projection than we are about his 2017 swinging-strike rate. Still, being moderately certain of a walk rate under 7% is a good thing to say about a young left-hander.

For what it’s worth, Steamer projects a 7.9% walk rate. That seems high. Manaea did struggle with command in the low minors, but that was in 2014 in High-A. He’d have to slide backwards badly to jump 1.7 points.

3. A High Home-Run per Fly-Ball Rate

Wait, why is Manaea’s 13.7% HR/FB rate a good thing? Because regression to the mean tells us this figure is unlikely to be so high in 2017. The following graph illustrates the year-to-year HR/FB correlation for Athletics starters since 2002:

I looked at only A’s starters here to somewhat adjust for park. The relationship year-to-year is weak (r = -0.12). My point isn’t that Manaea’s HR/FB will certainly go down; it’s that we don’t have much of a reason to suspect it’ll be this high again.

4. A Top-Five Out-of-Zone Swing Rate

The best reason to be optimistic about Sean Manaea is this: last year he induced hitters to offer at 36.5% of his pitches out of the zone. This rate ranks in the 98th percentile among starters who faced at least 100 batters last year:

Manaea ranks just about equal with Thor here and ahead of… well, nearly everyone else.

Out-of-zone swings are great for pitchers. Data from Baseball Savant shows that swinging at pitches out of the zone results in a much lower ISO than swinging at pitches in the zone:

Manaea’s high O-Swing% bodes well for suppressing power, especially in Oakland. This is another reason to suspect his HR/FB rate will drop next year.

Speaking of next year, the data show a moderate correlation (r = 0.57) between O-Swing% year-to-year:

Similar to Manaea’s walk rate, A’s fans can feel moderately good about Manaea fooling hitters in 2017. Even if his O-Swing% drops, it has a long way to fall.

Conclusion

Don’t get me wrong: Manaea isn’t a world-beater. He isn’t even the best pitcher on the A’s staff. That honor still belongs to Sonny Gray. Indeed, it’s possible that Manaea isn’t even the team’s No. 2; our Depth Chart projections put Jharel Cotton in that spot.

But Manaea’s projection of 2.2 WAR is solid. If 2016 is any indication, fans can expect him to induce a lot of swings like this in 2017: