Aaron Nola and the Rich Hill Prescription

One of the most interesting aspects of the Rich Hill story was his decision to break from convention and make his curveball – one of the game’s most effective pitches – his primary offering, a decision about which I wrote earlier this week.

That decision was one of a number of factors that has led to Hill’s late-career resurgence. As you’re probably aware, Hill led all major-league pitchers in curveball usage (49.7%) last season, throwing it more often than his fastball (47.2%). By this standard, Hill is an outlier. Conventional wisdom in baseball stipulates that the fastball should be the primary pitch for just about every arm. Rejecting that wisdom allowed Hill to become one of the most productive per-inning pitchers last season — and to receive a three-year, $48-million contract this offseason despite a limited track record of success.

The only regret Hill might have is that he didn’t change things earlier. What would Hill wish he had told a younger version of himself?

It’s that question which brings me to talented young Phillies starting pitcher Aaron Nola. Nola isn’t left-handed like Hill. His curveball doesn’t have quite the same shape. It is, perhaps, the next best thing to Hill’s curveball among major-league starters, however, depending upon how you judge performance and aesthetic beauty. It’s certainly part of a small group and a candidate in the discussion.

The curve tracks so well horizontally it made Jose Bautista flinch:

Nola appears to be able to manipulate the pitch, as well. Here it is against Bryce Harper, with more vertical movement against the left-handed star who swings over the pitch.

The pitch has a Wiffle Ball-like quality. It’s special…

Nola understands his curveball is a great pitch. He finished second in baseball in curveball usage among starters after Hill, tied with Jose Fernandez at 33.8%. Nola joined, Hill, Fernandez, Collin McHugh — McHugh is also in possession of an excellent curveball — as the only four starters to throw a the pitch at least 30% of the time.

But what if Nola threw the pitch even more? What if he was closer to Hill’s curveball usage rate than his own? What if the curveball became not his top secondary pitch – he also throws a changeup on occasion – but his primary pitch? What if he, too, went away from convention?

Overall, Nola combined to throw his two fastballs 57% of the time last season, though the combination resulted in a fastball liner weight of -5.5 runs that ranked 110th out of 142 pitchers who recorded at least 100 innings. Nola’s four-seam fastball is a solid if unspectacular offering. The pitch averages 90.3 mph, nearly two ticks below the MLB average for starters (92.1 mph). It ranked 69th in whiff/per swing (18%).

His two-seamer is a solid if unspectacular offering. It ranked 65th in whiff/per swing (11 percent) and 50th in GB/FB ratio last season among those who have thrown at least 200 two-seamers.

It’s his curveball that is a special.

Nola’s curveball ranked 13th in the sport in whiffs per swing (40.97%) and 27th in GB/FB ratio (4.17), right after the 26th-ranked Hill curveball (4.19). Eno Sarris ranked Nola’s curveball as the 19th-best overall pitch among starters in 2016, and the fourth-best curve among starers after Corey Kluber, Jose Fernandez and Jon Lester. (Hill’s curve didn’t meet the swinging-strike standards of Sarris’ ranking, but it is a rare called-strike weapon.) Hill led baseball in percentage of pitches taken as curveballs for strikes (10.55%), Nola finished 11th with (7.1%).

So in sum, Nola’s curveball is one of the best of its type at generating swings and misses, ground balls and pitches taken as strikes.

According to linear weights, Nola’s curve was the fifth-best among starters (9.3 runs better than average) after Kluber (21.8), Hill (16.0), Yordano Ventura (10.5) and Madison Bumgarner (9.4). (While baseball is trivial in perspective, the tragic deaths of Fernandez and Ventura have taken two of the best breaking pitches out of the game.)

Need more evidence of its greatness? Nola’s curveball ranked first in 2016 in horizontal movement last season and it also ranked first horizontal movement in 2015.

Now, perhaps the Phillies and Nola believe the curveball places more stress on his valuable right ulnar collateral ligament and shoulder. (Nola says his elbow is ‘100 percent’ healthy.) Perhaps they believe increasing its usage would take away from its effectiveness. But Hill’s curveball was still incredibly effective last year even though hitters knew they had coin-flip odds with Hill: half the time fastball, half the time a curve.

The curveball has another advantage: it’s not seen as often around the league. Among starters who logged at least 100 innings last season, 29 pitchers threw a slider at least 25% of the time. Only nine pitchers threw a curveball at least 25% of the time, according to PITCHf/x classifications. Last season, 8.8% of pitches were curveballs and 15.3% were sliders.

Nola is already a very good pitcher. He posted a 19-point K-BB% rate last season. He kept the ball on the ground with a 55% ground-ball rate. He was unlucky (60.6% strand rate), and I think it’s pretty clear he outpitched his 4.78 ERA. Nola posted a 3.08 FIP and 3.08 xFIP and 2.8 WAR in 20 starts.

Nola is already one of the better young starting pitcher in the game but by relying less on his fastball and more on his best weapon, by relying on the Rich Hill Approach, perhaps he could become even something more.