Every season is an opportunity for improvement, whether it’s addressing a weakness or refining a strength.

And over at Baseball Savant, there is now an easy way to see which players are rising (or falling) the most in a variety of advanced statistical categories. Meet the new year-to-year changes leaderboard.

Without further adieu, let’s dive in and take a look at 13 players who have authored some of the most significant improvements from 2019 to ‘20. The focus here is on those whose gains have helped keep their teams in playoff contention late into this abbreviated season.

All stats are through Tuesday’s games.

HITTERS

Hard-hit rate: Fernando Tatis Jr. (Padres), Corey Seager (Dodgers)
Change: +19.7% (Tatis), +19.5% (Seager)
The Padres and Dodgers are battling it out for the National League West title, with these two young shortstops playing a leading role. Tatis already was well above average at making hard contact as a rookie in 2019 (44.1%), but he has taken his game to another level this year, with an MLB-best 63.8% of his batted balls having an exit velocity of 95 mph or harder. Seager, fully healthy again this season, has easily the highest hard-hit rate of his career (57.7%), trailing only Tatis in that category, as well as total number of hard-hit balls (82).

Sweet-spot rate: Jason Heyward (Cubs)
Change: +15.0%
In his first four seasons with the Cubs since signing an eight-year, $184 million contract, Heyward posted a .711 OPS. Now the 31-year-old is suddenly hitting like a star (.286/.408/.521). The biggest difference? Heyward has cut down on both his ground balls and popups and turned them into line drives -- a far more productive output. And so there he is, just behind old pal Freddie Freeman near the top of the sweet-spot rate leaderboard. In 2020, 46.8% of Heyward’s balls in play have been hit with a launch angle between 8-32 degrees, generating a .628 batting average and 1.233 slugging percentage.

Pull rate: Robbie Grossman (A’s)
Change: +17.5%
Grossman, a 30-year-old with a history of getting on base but without much power, has a higher OPS this season than A’s teammates Matt Chapman (now on the injured list), Matt Olson and Marcus Semien. Grossman’s batted ball profile doesn’t look all that different, except for the fact that 46.7% of his contact has gone to the pull field. For a hitter without big-time power, it’s been a path to success. Grossman has pulled 13 of his 18 extra-base hits for the AL West leaders and is slugging .780 when hitting in that direction.

Chase rate: Kevin Kiermaier (Rays), Gio Urshela (Yankees)
Change: -13.2% (Kiermaier), -12.8% (Urshela)
These two AL East powers both rank in the top five in the Majors in walk rate, and this is one reason behind their patience. Kiermaier has never been a high-average hitter, but his newly keen eye (21.7% chase rate) has more than doubled his walk rate (13.6%), made him an above-average on-base threat and given him more of a chance to use his elite sprint speed. Urshela, who just returned from about two weeks on the IL, has lost more than 30 points of batting average from last year’s breakout campaign but raised his OBP (.376) in large part by dropping his chase rate from 40.1% -- a top-10 highest rate in 2019.

Expected wOBA: Teoscar Hernández (Blue Jays)
Change: +125 points
The second-generation names -- Bichette, Biggio, Guerrero -- get most of the attention in the Toronto lineup, but it’s Hernández who has emerged as the most important performer this season. After hitting at a slightly above-average level in 2018-19, the 27-year-old slugger has cut down on his strikeout rate while making some of the most elite contact in the game. The result is a top-10 xwOBA (.443), roughly equal to Tatis, and the biggest jump of any qualified player. While Hernández had been out since Sept. 6 with a mild oblique strain, he was activated on Wednesday, in plenty of time to help Toronto in October.

PITCHERS

Fastball velocity: Clayton Kershaw (Dodgers)
Change: +1.4 mph
From 2015-19, Kershaw’s fastball velocity dove from 94.2 mph to 90.3 mph, leading many to wonder if his heater was on a permanent decline. But Kershaw, as intense a competitor as there is, set to work reversing the trend. He has succeeded. As MLB.com’s David Adler wrote last month, it’s almost unprecedented -- in the pitch-tracking era (2008-present) -- for a starter to regain this much velocity after four straight years of decline. Kershaw and his 2.28 ERA have defied that. Next challenge: the postseason.

Strikeout rate: Shane Bieber (Indians)
Change: +11.1%
Bieber already produced one of the biggest jumps in K-rate among starters in 2019, going from 24.3% as a rookie to a well above average 30.2%. As it turns out, that was only the beginning. Bieber has continued to increase his reliance on his nasty array of secondary pitches, led by a curveball that gets misses on more than half the swings against it, netting 43 strikeouts. With a K-rate that has jumped to 41.3% -- which would be a record for a qualifying season -- Bieber became the fastest pitcher in history (62 1/3 innings) to get to 100 K’s in a season in his most recent start.

Whiff rate: Jacob deGrom (Mets)
Change: +9.2%
One might think that a pitcher who already has won back-to-back Cy Young Awards is as good as he’s going to get. But deGrom has been continually defying expectations for quite some time now. The 32-year-old righty has added even more fastball velo than Kershaw (1.6 mph), and both the heater and deGrom’s 92 mph slider are generating more swings and misses than ever. That’s how an 84th-percentile whiff rate becomes a 98th-percentile whiff rate, with deGrom’s 40.7% mark trailing only Bieber among starters and spurring a serious run at what would be a momentous third Cy (as long as the right hamstring spasm that forced him from Wednesday's start isn't serious).

Barrel rate: Lucas Giolito (White Sox), Kyle Freeland (Rockies)
Change: -4.9% (both)
Giolito has followed up his breakout 2019 by being just as good -- if not better -- this season. Inducing more grounders to go with his better-than-average hard-hit rate, the White Sox ace has allowed only six barrels (balls with optimal quality of contact) out of 134 put in play against him (4.5%). Freeland has been even better in that regard (3.9%), helping him bounce back from the nightmarish 2019 (6.73 ERA) that followed his breakout ‘18 campaign. With more grounders and fewer hard-hit balls, he has joined Giolito among the league leaders in this category.

Expected BA: Corbin Burnes (Brewers)
Change: -75 points
Bad luck was a big problem for Burnes in 2019. His .279 xBA wasn’t good (.250 was MLB average), but on top of that, the 51-point gap between his actual batting average allowed (.330) and his xBA was among the largest in the Majors. One of the highest BABIP figures in MLB history will do that. But everything has turned around for Burnes in 2020, a boon for the contending Brew Crew. Between a skyrocketing K-rate and weaker contact, Burnes is responsible for the biggest xBA drop of any MLB starter (down to .204). The cherry on top? This year, his actual average allowed is 50 points lower than that.