Jason Kipnis was the Indians' best player in 2013. He was their best player again in 2015. In the season between, he was not only not their best player, he was one of their worst, among the starters. His OPS+ yo-yoed from 130 to 80 to 121 during those three seasons. His WAR went from 5.7 to 0.7 to 4.6. Among Tribe fans, the commonly held explanation for this is that the oblique injury Kipnis suffered early in 2014 is to blame. It recovered enough for him to get back on the field, but not enough for him to play like himself. This is a comforting thought because it tells us that when Kipnis plays like himself, he's an All-Star. It's also a completely logical explanation.
Still, I found myself wondering how many other players have had a three-season like that with such a dramatic chance from very good to very bad to very good again, and I found myself wondering how those players did in the fourth year of that trend.
I decided to focus on second basemen and the players they're most similar to, third basemen and shortstops. I also decided to focus on players in their 20s, so that the downward slope of the aging curve wouldn't really be an issue. My final decision was to (somewhat arbitrarily) go back 50 years to look for players. I set the benchmarks for "similar" at 4 WAR and an OPS+ of 115, and then used Baseball-Reference's Play Index and looked for players with two such seasons in a three-season stretch, and then eliminated the ones whose good seasons were consecutive, so that I'd be left with the ones like Kipnis, whose production dipped between two very good years.
I found 26 players who met the criteria, one of whom appeared two different times, for a total of 27 data points (each player is listed with their age range for those three seasons):
- Joe Morgan (21-23)
- Pablo Sandoval (22-24)
- Edgardo Alfonzo (23-25)
- Jose Reyes (23-25)
- Robin Yount (24-26)
- Chipper Jones (24-26)
- Robinson Cano (24-26)
- Bill Madlock (25-27)
- Cal Ripken (25-27)
- Matt Williams (25-27)
- Robin Ventura (25-27)
- Evan Longoria (25-27)
- Rico Petrocelli (26-28)
- Toby Harrah (26-28)
- Eric Soderholm (26-28)
- Lou Whitaker (26-28)
- Alan Trammell (26-28)
- Howard Johnson (26-28)
- Jeff Cirillo (26-28)
- Edgardo Alfonso (26-28)
- Nomar Garciaparra (26-28)
- Troy Tulowitzki (26-28)
- George Brett (27-29)
- Tim Wallach (27-29)
- Gary Gaetti (27-29)
- Morgan Ensberg (27-29)
- Dustin Pedroia (27-29)
While each of those guys met my criteria, I wasn't looking for guys who might have just missed the cutoff in their middle season, I was looking for players who (like Kipnis) were below average.
Soderholm missed his entire middle season; Garciaparra missed all but 21 games of his; Tulowitzki missed all but 47 games; Longoria all but 74 games. Each of them was a good player for the stretch of the season they appeared in. Ignoring those four, as well as those who were still good in their middle season (just not quite as good), you're left with the following list (with their age during that middle season):
Pablo Sandoval (23): His OPS+ dropped from 144 to 99 in his middle year, before going all the way to 155 in his rebound season. His WAR went from 4.3 to 1.5 to 6.1. In the season following his rebound, Sandoval played in 108 games, with an OPS+ of 123, and 2.1 WAR.
Robinson Cano (25): His OPS+ went from 119 to 86 to 121 for his three years, and his WAR went from 6.7 to 0.2 to 4.5. The season after his rebound, Cano played in 160 games, with an OPS+ of 141 and 8.1 WAR. He was among the very best players in baseball during the five seasons after his rebound, with an average of 7.3 WAR and an OPS+ of 142. 22.8
Bill Madlock (26): His OPS+ went from 151 to 111 to 144 in those three years, and his WAR went from 4.3 to 1.0 to 4.8. The season after his rebound, Madlock played in 154 games, with an OPS+ of 116 and 2.2 WAR. He had two very good seasons later on in his career (age 30 and 31) as well.
Matt Williams (26): During those three years, his OPS+ went from 129 to 93 to 137, and his WAR went from 5.4 to 1.8 to 5.8. In the year following his rebound, Williams played in 112 games, but that was the strike-shortened 1994 season, so 112 games meant playing in all but three of his team's games. His OPS+ that year was 141, and he was worth 4.7 WAR, which prorates to 6.6 over a full season. Williams was an above-average player in each of the next six seasons after his rebound and was worth 4+ WAR in four of those seasons.
Edgardo Alfonzo (27): His OPS+ went 147 to 90 to 128 during those years, and his WAR went from 6.4 to 1.5 to 5.0. In the year following his rebound, Alfonzo played in 142 games, with 0.3 WAR and an OPS+ of 90. Alfonzo was finished as even an average player after his rebound season when he was 28.
Alan Trammell (27): His OPS+ went from 136 to 90 to 120, a good match for Kipnis. Trammell's WAR went from 6.7 to 3.0 to 6.3, which means he was still above average in his down year, but the dip is big enough (and the OPS+ a good match), so I'm including him here. He played in 151 games during his rebound season, with an OPS 155+, and 8.2 WAR. He probably should have won the AL MVP. Beyond that excellent season, he had three other years in which he was worth 4+ WAR later in his career.
Tim Wallach (28): For those three years, his OPS+ went from 115 to 93 to 121. His WAR went from 6.1 to 2.3 to 4.2, so like Trammell, he was still a little better than average in his down year, but his bat dropped to below average. The season after his rebound year, he played in 161 games and put up an OPS+ of 125 and 4.1 WAR. That was his last season as even an average player though.
Gary Gaetti (28): His OPS+ went from 131 to 102 to 148, and his WAR went 5.8 to 2.3 to 4.3, which means he was slightly above average for by both metrics in his down season, so feel free to discount him from this discussion, if you like. The year after his rebound, Gaetti played in 130 games, with an OPS+ of 88 and 1.7 WAR. He had a long career, with six seasons later on in which he was roughly average or better, but his rebound was his last year with 4+ WAR.
Morgan Ensberg (28): His OPS+ went from 131 to 90 to 144, and his WAR went from 4.8 to 0.5 to 6.2. In the season following his rebound, Ensberg played in 127 games, with an OPS+ of 120 and 3.5 WAR. That was his final season as even an average player, though, and he played his final game at the age of 32.
This pool of players is too small to establish much confidence in the findings being applicable for Kipnis or anyone else who comes along and has three seasons like Kipnis' last three. Still, I find it comforting that most of the players a stretch like Kipnis did wound up being a good player again the following year, and a third of the players were better than ever in the season following their rebound.
Those nine players were worth an average of 4.1 WAR in the season following their rebound, which means they didn't quite maintain their rebound-season production, but were still very good. I'd certainly be happy with Kipnis posting 4.1 WAR this season. Over the three season following their respective rebounds, those nine players were worth an average of 8.8 WAR, which is a little lower than I'd hope to see from Kipnis, but still represents above-average play.