Sprint speed affects many fantasy-relevant abilities; beating out infield singles, stealing bases, scoring from second on a single, being removed for a pinch runner, etc. Projection systems like Steamer do a good job incorporating sprint speed to project stolen bases, but it doesn’t seem to be factored in enough for runs scored – especially when there are recent changes to a player’s sprint speed profile. To address this, I looked at players with >400 PA and at least 75 “competitive runs” in each of the two previous seasons. For the purposes of this article, I will exclude HR from all times on base and runs totals.

The results: players who suffered a decline in sprint speed >0.5 ft/s in the previous season (sample: 99 hitters) scored 2.9 fewer runs per 170 times on base relative to their Steamer projection, compared to those who neither lost nor gained more than 0.1 ft/s the previous season (93 hitters). That jumps to 5.7 fewer runs scored for hitters that declined >1.0 ft/s in the previous season (14 hitters). Here are those 14 hitters along with how many runs they lost prorated to 170 times on base, compared to their Steamer projection.

Age doesn’t seem to be much of a factor. The two youngest – 22 year-old Vladimir Guerrero Jr. and 24 year-old Francisco Lindor – did regain a lot of their lost speed, but so did the two oldest – 34 year-old Josh Donaldson and 39 year-old Adrian Beltre. Meanwhile, neither of the the next two youngest – 25 year-old Manny Machado and 26 year-old Gregory Polanco – regained any of their lost speed.

The following table shows all of the hitters that had a sprint speed decline in 2021 of at least 0.5 ft/s and a top 300 ADP in NFBC Draft Champions leagues since Dec. 1. The table also includes mid-season sprint speed decline in 1st Half vs 2nd half if the player had at least 10 competitive runs in both halves.

While we can assume these players will have their runs scored affected as described above, there are some players here to be particularly concerned about. Mookie Betts dropped to 27.1 ft/s and had poor success stealing bases. After getting caught 5 times in 15 attempts in 2021, this may no longer be a big part of his game.

Giancarlo Stanton – the inspiration for this deep dive – is Exhibit A for why sprint speed matters for more than just stolen bases. His sprint speed in 2021 fell squarely between Rowdy Tellez and Dan Vogelbach. He would have had to score 20 additional runs during his 170 times on base to match his projected rate of runs per times on base. Some of that is likely due to variance, but he was often removed for a pinch runner late in games, and cost his team -7 runs with his base running when he was allowed to remain in the game. We can use player history to project Runs/PA for players who have always been slow, but rapid declines like Stanton had in 2020, and again in 2021, take a year or two to be reflected – especially when those changes occur in small sample sizes. The following table details Stanton’s recent decline.

Ketel Marte saw a continued decline, dropping to 26.7 ft/s after a peak of 29.2 in 2017. Like Jose Altuve before him, he may be losing stolen bases from his game a little bit earlier than we expected after a pivot to being more of a power hitter. Those doubting his low SB projection and hoping for a speed resurgence may want to temper their expectations.

Luis Robert had a serious decline in sprint speed after his return from a torn hip flexor. Here is how it looks over the past couple of seasons.

He did have a revelation at the plate after returning from injury, but only attempted one stolen base in his final 37 games. While an offseason of rest could allow his hip to fully heal, he may not be the source of speed you were looking for at the 1/2 turn.

The granular sprint speed data referred to above can identify sudden mid-season declines which projection models may not fully take into account. I only have this data for 2021, so I’m unable to back-test it. The following table includes the most notable players who had large mid-season drops in sprint speed with at least 25 competitive runs in each half.

The biggest red flag here is Alex Bregman, who prior to his quad injury had already lost 0.8 ft/s from 2020. After 10 weeks on the IL he returned down an additional 1.9 ft/s. He’s had a series of soft tissue injuries to his legs (hamstring/quad), in addition to off-season wrist surgery this past November on the same arm he had surgically repaired in 2019 to address other chronic issues. Even with an ADP outside of the top 100, he’s a significant health risk.

Rafael Devers didn’t have any injuries that should have affected his running, but he still saw a notable decline in sprint speed some time around August. In July he was up to 27.5 ft/s – a full 1.0 ft/s over his 2020 average – which fell back down to 26.2 for the second half of the season, giving him a final season total near his recent career average. This could be a case of entering the year in the Best Shape of his Life^TM, and simply not maintaining his conditioning throughout the season. Perhaps it’s a pattern. I don’t think it’s a major concern, but he may be hard-pressed to net his usual handful of stolen bases, especially considering his 50% success rate since the start of the 2019 season.

Leg injuries are no stranger to Yordan Alvarez. After a hamstring injury in July – which didn’t require a stint on the IL – his sprint speed dropped to 25.1 ft/s. He was able to return to his 1H average of 26.5 in September. Stolen bases are not the concern here, but rather his ability to stay on the field at all.

Paul Goldschmidt played almost every game of the 2021 season, with the only real injury being a sore back on opening day. He had a slow and steady sprint speed decline that lasted the entire season, capped off with a 25.4 ft/s mark in September, when he still managed to go 2-for-2 in SB attempts. He’s simply getting old, but his ability to remain successful picking his spots should allow him to continue to make positive SB contributions despite losing a step. However he may receive more days off throughout the season to keep his legs fresh.