Nate Eovaldi: Quietly Improving?

Note: This was written before his most recent, pretty bad start against the juggernaut Baltimore offense in Camden Yards.

In recent seasons, the Yankees rotation has seemed like just Tanaka and a bunch of uncertainty. Michael Pineda has flashed brilliance and put up huge K%-BB% numbers, but has been all too "hittable" and prone to starts with lots of ERs. He has been very inconsistent. C.C. Sabathia has been hurt and throwing 88 mph fastballs. That leaves the back end of the rotation, where the shaky Ivan Nova and Luis Severino have resided. Severino is now in AAA figuring things out.

The astute reader will notice I have left out one member of the rotation. A guy whose name is in the title of this very post. He was solid, but not spectacular for the Yanks in 2015, putting up a 4.2 ERA, 3.42 FIP, and 3.81 xFIP. Or basically, a slightly above average AL starter (AL average xFIP was 4.1).

Lost in that season-long number is a change he made in June of last year. See if you can spot the change in the chart below.

Yes, that splitter usage shot up. He has maintained most of that increase into this season. Let's look at a table showing his performance before that change in usage and after.

Dates	ERA	FIP	xFIP	K%	BB%	SwStr%
April 2014-May 2015	4.38	3.53	3.79	16.60%	5.20%	8.30%
June 2015-June 2016	3.94	3.22	3.63	20.30%	7.50%	9.30%
2016 Season	3.71	3.53	3.38	22.90%	6%	9.30%

You can see that he has improved almost across the board since he made that change (compare row 1 and 2). The 2016 season is included in both rows 2 and 3, just for kicks so you can see this year specifically. So, that's a positive change and something worth celebrating.

One thing he still needs to work on his using his curveball too much the third time through the order.

This graph is just for this season, but it looks very similar for last season. The curveball gets crushed after hitters have seen it a few times. He hasn't addressed this issue yet, but he should probably replace a few curves with changeups (as you will see later).

Some things he has changed already this year are his slider and split finger velocities, but mainly his slider speed. The two pitches were almost the same speed in April, but he has slowed down his slider since then.

This has affected this slider movement, causing it to drop more.

He seems to have done this partially by adjusting his position on the rubber.

Regardless, he has made another tweak here, after increasing his splitter use last year. Let's see how that change has worked out.

	ERA	FIP	xFIP	K%	BB%	SwStr%
April 2016	4.38	3.57	3.09	28%	5%	9.90%
May 2016	3.25	3.51	3.58	19.50%	6.70%	8.90%

Well, that's not what I was expecting to see. Despite a better ERA and FIP, everything else is worse after that change. It looks like he should go back to the April position. Keep an eye on this throughout the season to see if he adjusts back. He's getting good results right now, so he probably won't change, even if his peripherals are getting worse.

One thing is that his four seam whiff/swing % has jumped from 13.92% (73rd) in April to 24.8% (12th in MLB) in May. However, all his other pitches got worse in that category, so it came at an expense.

Looking at his Pitch F/X data further, it seems that his four seam and splitter are both great pitches for getting swings and misses. Both have SwStr% above average. His slider is awful and his curve is even worse (0 whiffs on 61 curveballs so far!). He doesn't seem to trust his changeup, but it is actually doing well this year (18.2% SwStr%). With his curve and slider struggling, it might be time to up the changeup usage. If he does that, he's got some strikeout upside.

I'm sorry that I couldn't come to a solid conclusion for you here. Eovaldi's a complicated man. His change made in 2015 to throw more splitters has worked well, but his change in position on the rubber in 2016 has been a bad idea. He doesn't trust his good changeup (which might not get the same swings and misses if thrown more, to be fair) and he's got a bad curveball that is killing him. There is room here for even more improvement, but he has made himself ownable in most leagues with his changes so far and you have to like a guy that is constantly trying to get better. Tschus!