Could Josh Hader Have Become a Starter?

Last week, David Laurila asked me an interesting question. He’d been talking baseball with some baseball players – it’s true, we really do have great jobs – and the conversation landed on Josh Hader. That got Laurila thinking about Hader’s similarities to Spencer Strider. The crux of the discussion: Would Hader have ended up as a lefty version of Strider if, after appearing in the major leagues as a reliever, he’d transitioned back to the starting role he held in the minors?

I love questions like this. They’re fun to research, and I also feel no pressure to reach a definitive answer. Would Hader have ended up as a great starter? It’s clearly unknowable. That gives me a lot more latitude to speculate. In addition, this question isn’t just about Hader. It’s about whether future pitchers with Hader-esque profiles make more sense as starters or in the bullpen. No wrong answers and broad implications? Sign me up.

First things first, let’s talk about what it means to look like Strider as a starter. Strider has two standout pitches, but it’s really one standout pitch and a capable understudy. His fastball explodes through the top of the zone and screws hitters into the ground. It’s not so much the velocity – though that doesn’t hurt – but the shape and release point that combine to bamboozle opposing hitters.

Stated in numbers, Strider releases the ball from a fairly normal spot – just under six feet off the ground – but then things get wild. His fastball drops two or three inches less than the average four-seamer thrown with similar velocity thanks to a ton of spin. It also comes into the strike zone at a shallow angle thanks to a combination of spin, release point, velocity, and location. His -4.39 VAA (vertical approach angle) is comfortably more shallow than league average. Last year it was even shallower – a lower release point and slightly more velocity put him in Jacob deGrom territory.

Hader throws a similar fastball, in function if not in form. He’s left-handed, which is a clear difference, and Baseball Savant classifies his main weapon as a sinker instead of a four-seamer. Call it what you want, though, it still behaves like a four-seam fastball. He imparts a similar amount of vertical break on the ball, and it’s almost all vertical movement. If you thought Strider’s fastball came in flat, Hader’s is in a different category altogether. From a 5-foot-7 release point, he spins his way to a -3.84 VAA. That’s essentially the same as deGrom, whose fastball is the platonic ideal of new-age pitch design.

If you only care about fastball shape, Hader would clearly fit as a top-of-the-rotation starter. But there’s a lot more to pitching than that. When he made it to the majors in 2017, Hader was dealing with extreme command issues in the minors. He was striking out just 22.4% of opponents in Triple-A and walking 13.6% as a starter. Even as he laid waste to the majors that year, to the tune of 68 strikeouts in 47 innings (36.2% strikeout rate), he walked far too many batters. It’s hard to control a pitch with such explosive movement; he was throwing 80% fastballs and still piling up walks.

That probably made Milwaukee’s decision to leave him in the bullpen easier, but the Braves faced a similar decision with Strider and chose differently. Strider, too, walked more than his fair share of batters in the minors. When he made it to the majors for good in 2022, it was as a reliever. Even then, he walked 11.6% of opposing batters across 24.1 innings. Strider’s relief turn looked a lot like Hader’s debut year.

When he transitioned to the rotation, Strider hardly changed his pitch mix. He’s been roughly two-thirds fastballs and one-third sliders the whole time, with a smattering of changeups to keep opposite-handed hitters honest. He didn’t even start throwing more strikes. But he started walking fewer batters anyway, and to be quite honest, he probably would have walked fewer batters even if he’d remained in a relief role. The Braves simply took a look at his underlying numbers and realized things would normalize.

Strider was throwing plenty of strikes. His zone rate spiked when he got behind in the count by more than an average major league reliever. He missed a ton of bats despite that direct approach. There was no reason to look at Strider’s raw pitch data and think he’d continue to walk a raftload of batters, and so the Braves told him to keep doing what he was already doing, only from the rotation.

Want to know the weird part? Hader’s numbers in his first major league season look fairly similar to Strider’s relief stint. Here are some numbers related to walk rate for 2017 Hader and 2022 Strider in relief:

If there’s a difference, it’s that Strider was commanding his fastball for a strike slightly more frequently in disadvantageous counts. But these are strikingly similar numbers overall, and players with stuff as electric as Hader’s often improve their command over time through sheer repetition. Lo and behold, Hader’s walk rate plummeted over the next two years, even as he started striking out more batters.

I thought this was kind of strange, because Hader hasn’t held onto that command over the years. As he transitioned from a multi-inning reliever to a prototypical closer, his walk rate has started to creep back up, and it’s at a career-high 13.7% this year. But there’s a lot of contingent history here. Hader surely trains differently as a one-inning closer. He faces different batters. Walks have vastly different contextual value in the ninth inning; sometimes they’re far less important based on the base/out state. Hader has also started throwing harder, and his fastball command has gone down commensurately. I don’t think it’s an apples-to-apples comparison when we’re wondering what might have happened if he changed things half a decade ago.

Let’s get back on task. We’re wondering whether Josh Hader’s career would have turned him into a lefty Spencer Strider if he’d transitioned back to starting after reaching the majors. We’ve already answered two questions: Hader’s fastball looks a lot like Strider’s, and their walk rates as relievers belied solid underlying command. Next, let’s get to what I hear many people mention as a reason to keep two-pitch pitchers in the bullpen: platoon issues.

I don’t think this is much of an issue for Hader, to be honest. As a lefty, he gives opposing managers a fairly easy decision when he enters the game. If there’s a mediocre lefty due up, it’s a near-automatic pinch hitting situation. If Hader were a starter, those mediocre lefty batters would just get the day off instead. He’s faced only 26.3% lefty batters in his career. Lefty starters face just 19.8%, true, but the lefties Hader faces are almost exclusively great.

Both Strider and Hader have arsenals that shine against opposite-handed batters. Four-seam fastballs – again, whatever you want to call it, Hader’s fastball behaves like a four-seamer – do well against hitters of all varieties. They both throw gyroscopic sliders, which are much better than the sweeping variety against opposite-handed hitters. In addition, good pitchers are just good – a shocking revelation, I know. Hader has allowed a .250 wOBA in his career against righty hitters. Strider checks in at .268 against lefties. Those are elite numbers, and that’s despite both of them having elevated platoon splits relative to league average. If you’re as good as they are, handedness just isn’t that big of a deterrent.

A larger issue, in my eyes, is the times through the order penalty. It’s not clear whether a wider array of pitch options makes pitchers perform better as they face batters multiple times, but it certainly makes sense in my head. Strider hasn’t seemed particularly bothered the second time through the order, but we simply don’t have enough of a sample to say. And we have even less with Hader, because even when the Brewers used him as a multi-inning weapon, he almost never faced the same guy twice. He’s faced only 12 batters for a second time in his major league career, a small enough sample that I’m just going to ignore it completely.

That leaves me grasping for straws when it comes to examining Hader’s viability as a starter because quite honestly, his per-batter statistics have been off-the-charts excellent throughout his career. The real question is whether he’d be able to sustain that form with a starter’s workload. Again, I think that Strider’s transition is instructive, so I decided to compare apples to apples as best as I could.

In Hader’s rookie season, he exceeded the 20-pitch mark in 17 separate appearances. When Strider started out as a reliever, he did so eight times. That gave me a chance to compare how they each fared when they had extended outings. I focused on two things in particular: fastball velocity and zone rate. It’s hard to find one metric that explains pitcher fatigue, but I think that those two each help understand what’s going on.

Hader came out of the gates hot in 2017, averaging 94.7 mph on fastballs he threw among his first 10 pitches of an outing. But he tailed off quite a bit from there, with his velocity dropping by roughly 0.7 mph by the time he reached pitches 21-30. That sounds like a lot, but here’s a counterpoint; Strider’s velocity as a reliever showed a similar dip. He came out pumping 99.3 mph on average, then saw a 0.9 mph decline by pitches 21-30.

What about command of the strike zone? Hader’s diminished over time. His zone rate on pitches 1-10 was 66.3%, then 62.8% on pitches 21-30. More broadly, he had a 67.5% zone rate on pitches 1-20 and 62.1% thereafter. Strider displayed a similar pattern in both respects. He had a 70.9% zone rate on his first 10 pitches in relief outings, then 64.6% from pitches 21-30. He had a 64.3% zone rate on his first 20 pitches and only 56.9% thereafter. If location is a good proxy for how tired pitchers are getting, Strider and Hader both seemed to tire similarly as relievers.

This whole article is an exercise in guesswork, to be clear. There’s no way to truly answer this question. We don’t know how Hader’s development would have changed if he had transitioned back to being a starter in the majors. His actual career has been excellent, so you can hardly say the Brewers made the wrong decision. He’s been one of the best relievers in baseball for a long time, and he’ll get a handsome contract in free agency this year.

At the same time, a lot of the things that made Hader stand out as a reliever look just like Strider’s initial foray into the majors, and we all know how Strider’s career arc has bent. He’s one of the best starters in the game, and starters just matter more to a team’s success than relievers, at least on a per-pitcher level.

The best I think I can tell David Laurila, in this post that would have been far too long to send to him over Slack, is that the answer is complicated. I can’t say for certain whether Hader would have become a nasty two-pitch starter, but the signs were all there. There’s a real Robert Frost vibe here – two relievers diverged in a wood. I’m not sure which one was less traveled, but both paths look pretty great. Ace reliever or ace starter – perhaps Hader had more options to succeed than everyone thought at the time. Perhaps Strider did too, for that matter. I guess the lesson is just that good pitchers are good, and that sometimes there are no wrong choices.