There’s been plenty of really, really stupid hot takes on Ivan Nova over the last couple months. How his contract is a disaster. How the Pirates need to trade him. My dad claimed to find an op-ed that he was the worst Pirate starter this year. I haven’t found said post myself, but if the writer happens to be reading this: your opinion is bad and you should feel bad. Did you forget that Tyler Glasnow was a thing?
Despite some pretty, shall we say, “questionable” opinions on the Pirates’ veteran righty, it’s ok to be disappointed with his second half performance. A 5.83 second half ERA isn’t going to cut it. The Pirates need him to be a middle of the rotation arm.
Some regression was expected. As amazing as his April was, nobody expected him to maintain it for a full season. And regress he did. Nova’s 4.14 season ERA perfectly lined up with his first half FIP. This was a rather aggressive fall to the mean, though. It’s safe to say this was more than just a bad bounce or two a game: Nova struggled.
So what was different? His pitch selection was mostly the same, though he seemed to do better when he threw his curveball less. He recorded a 2.72 ERA and .943 WHIP in his seven starts where he threw it less than 20% percent of the time. While it would be easy to say to ease up on the hooks, in the seven starts where he threw it at the highest rate, he recorded a healthy 2.89 ERA. It also was his best pitch according to Fangraphs’ pitch value (5 runs above average) and generated the best whiff rate (17.2 percent, according to Baseball Savant). Throwing your best pitch less isn’t a great strategy. Let’s put a pin in that.
Venue may have played a role. Eight of his first 16 starts were at home, but 11 of his last 15 were on the road. He pitched much better at home, going 8-2 with a 2.80 ERA at PNC Park compared to 3-12 with a 5.02 ERA as the visitor. Teams may have also caught onto his aggressive pitching and attacked the first pitch more often. Batters hit .138 on the first pitch of the at-bat in April. They hit .364 in the second half. And, of course, he had the audacity to walk the occasional batter, which mucked everything up.
These are all good trends, but they all sound like symptoms. We’re trying to get to the root cause of what happened in the second half. That brings us to the most common explanation: fatigue.
The coaching staff eventually came to the conclusion. It’s a reasonable assumption since Nova was in the middle of his first year as a full-time starter and already threw a career high amount of innings. He started to sputter at the part of the season where he would either be demoted to the bullpen or sidelined with injury.
He disagreed, and he had a case. His velocity and pitch movement held fairly steady, and his xFIP between the first and second half was nearly identical (4.17 in the first three months vs. 4.22 in the last three).
But pitching is more than just results; it’s mechanical. And there was a noticeable mechanical change happening around the time he started to stumble: his release point fluctuated. A change in release point can indicate an injury or fatigue. This is probably the best evidence to support the fatigue theory.
We can notice a notable drop in Nova’s average horizontal release point in July. From there on, he was clearly not throwing the ball from the same spot as he was in April. The ball was going further away from his body.
It takes a slight jump up in August and September, but that was heavily aided by some crazy outliers. If you look at his game by game release points, he was either continuing to decline or way off his normal season mean.
Nova seems to do his best work when the horizontal release point on his fastball is around -2.3 to -2.5 feet. He hit that sweet spot with his two-seamer in seven of his first eight starts of the season and fell 0.01 feet away from making it eight of his first nine. Nova had a 2.48 ERA in that stretch. He hit the sweet spot just once in the second half of the season: a six inning outing against the Brewers in August where he was charged with just one earned run.
We saw this take precedent with his left-handed/right-handed splits. Nova did fine against southpaws in the first half, holding them to a .328 wOBA and a 3.20 ERA. Again, for the most part, he was in the sweet spot. In the second half, they recorded a .425 wOBA and lit him up for a 7.66 ERA. His average release point took a dive around then.
For reference, here is his fastball chart.
Meanwhile, look at his average release points against right-handed batters. His second half averages are almost identical to how he pitches lefties in the first half. His wOBA against righties was fairly close too: .354. How much of that split is due to the hand advantage and how much is due to the arm slot?
It’s also worth pointing out his average release point started to lower before the second half of the season. Both his four-seam and two-seam release points begin to take a dip after his start in Baltimore in June. He was pulled from that start with left knee inflammation. Nova didn’t miss any time because of the inflammation and his next two outings were even quality starts. His release point was fairly close to the season average then, but I think this might have been the turning point in his season. He might have made a change, even subconsciously, to release the ball slightly different so his delivery put less pressure on his landing knee. It could have been a bad habit that stuck.
So if the release point was the culprit for Nova’s second half slump, can we expect him to improve in 2018? Possibly. If my hunch is right that his knee made him make an adjustment that he never reverted back from, then maybe a full season of April/May Nova is not outrageous. But it may come down to if he can find a comfortable arm slot.