On first glance, nothing notable jumps out about Lucas Sims‘ 2019 season. The right-hander pitched 43 innings with the Reds, posting an uninspiring 4.60 ERA, 4.45 FIP, and 4.57 xFIP. Take out his four spot starts and his ERA was better in relief (3.42), but the FIP (4.47) and xFIP (4.34) were not. Those peripheral numbers scream middle reliever who bounces between Triple-A and the majors — depth every team needs, though nothing particularly exciting. With Sims, however, it doesn’t require squinting to see there’s more potential yet to be unlocked as he heads for a full-time bullpen role in 2020.
Without watching him in action, the number that jumps off the FanGraphs page is Sims’ strikeout rate. Bordering on elite at 32.2%, it demonstrates his nasty stuff and one of the most important abilities a pitcher can have: missing bats. As a reliever, the numbers got even better. Sims struck out 36.4% of the hitters he faced. That ranked 15th among 335 relievers who threw at least 20 innings, above pitchers like Aroldis Chapman and Brad Hand. Yes, it was a fairly small sample, but it showed some of the tantalizing potential that made Sims a former top prospect with the Braves and the Reds’ primary target in the Adam Duvall trade in 2018.
Sims doesn’t have velocity that turns heads — although he has gained 2 mph since 2017 and generally thrown harder in relief — but he has a plus curveball and slider that he can spin better than almost any other pitcher in the game. He’s one of many Reds pitchers who saw a sizable jump in his spin rate under the tutelage of Derek Johnson and Caleb Cotham. Sims also gets more spin on his four-seam fastball than all but seven pitchers.
The curveball and slider were the primary sources of his dominance when he was on top of his game, holding hitters to a .222 and .153 xwOBA, respectively. The slider was his primary source of whiffs, generating a miss on an astounding 55.2% of swings and a chase rate of 43.8%. The curveball is the pitch Sims best controls, hitting the strike zone 46.2% of the time he threw it, solidly above league average.
Both breaking balls have similar movement, breaking horizontally more than they drop, with their separation coming in a two-mph difference in velocity. Sims’ curveball gets 2.8 inches more horizontal movement than the average curveball with similar velocity and arm angle. The slider gets 3.3 more inches than average.
The fastball, despite its elite spin, can get a lot better. Batters managed a .258 expected batting average and .328 xwOBA — both below league average against it in 2019. And while he allowed a .606 slugging percentage on the pitch, the expected rate (.449) was below league average, as his focus on throwing the ball up in the zone led to an excellent 17.0% pop-up rate. Still, Sims allowed an average exit velocity of 90.2 mph with the pitch, worse than the league average four-seamer.
But the biggest problem with the pitch is that Sims doesn’t throw it for strikes consistently. It’s a huge reason for his persistent control problems throughout his professional career. He had a 10.7% walk rate in 2019, a concerning number that is the largest factor in his mediocre peripheral numbers.
Here’s the stat that stands out about his fastball: 302 pitchers threw at least 300 four-seam fastballs in 2019, and only one hit the strike zone at a lower rate than Sims.
It comes as no surprise, then, that his walk rate was so high when his fastball was his most-used pitch. Sims featured the heater 50.1% of the time, and he leaned on the pitch heavily when behind in the count (60.3%). The curve came in at overall usage rate of 24.8% and the slider at 19.0%.
Sims, as someone with a high-spin fastball should, subscribed to the notion of throwing the ball up in the zone. That’s the ideal spot for swings and misses because batters expect the ball to have a certain amount of drop as it approaches the plate, and a high-spin fastball doesn’t drop at the same rate as an average-spin one.
The problem? Sims often threw the ball too high and/or missed to his arm side.
Batters caught on to Sims’ control problems with his fastball and started swinging at it less and less as the season moved on.
Given Sims’ challenges with controlling the four-seamer, it could make him another candidate for a change in pitch mix. Last year saw Robert Stephenson and Amir Garrett have tremendous success out of the bullpen when they started featuring sliders as their primary pitches. Stephenson, in particular, struggled to control his fastball and often missed to his arm side as Sims does, yet still threw it most of the time. Featuring the slider as his primary pitch turned his career around and kept him in Cincinnati. What works for some pitchers may not work for everyone, but it wouldn’t be a shock to see Sims increase his breaking ball usage in 2020.
That said, Sims certainly shouldn’t ditch the fastball altogether. His ability to spin it can make it a weapon when he locates it well. Sims got a 26.5% whiff rate on his four-seamer, well above the league average on the pitch (21.8%). There’s room to get better in that department, too.
Raw spin rate isn’t the only component necessary to make batters swing through the pitch. To minimize how much the four-seamer drops, a pitcher also needs to maximize their spin efficiency, or active spin. A fastball with pure backspin, or 100% spin efficiency, is ideal, though probably not possible for human beings. Justin Verlander was the closest thing to a robot we saw last year, registering 98.5% spin efficiency with his fastball. Sims came in at 84.8%, which was in the middle of the pack. Improving on that number would unlock more bat-missing potential for Sims — and between the forward-thinking coaching staff and technology available, the Reds have plenty of resources to help him do so.
But if Sims can’t improve his command of the four-seamer, it may behoove him to mix in more curveballs, which he can get over the plate with more regularity, and sliders, which batters are still swinging at even when they’re not in the strike zone.