For this one, the premise is simple: which players had the best last seasons of their careers? There are, however, a few caveats: players who died during the season or in the offseason do not count, while players who ended their career due to injury do. Also, I gave preference to full seasons (sorry, J.R. Richard) because I wanted to see the full breadth of a player's work right before they quit the game. So, without further ado...
1. Sandy Koufax, SP, 1966 (LAD): 27-9/190 ERA+/317 K
This feels like cheating, but it's not. Koufax was still unquestionably in his prime in 1966. Due to arthritis, 1966 was also his last season. From looking at the stats, however, you'd never know Koufax wasn't playing at full strength. I try to stay consistent which which statistical categories I use for each position, but I have to break that rule for Koufax. He was just so good, showing his WAR (an extremely impressive 10.8) doesn't do him justice. Playing through pain, he threw 27 complete games, in which he racked up 317 strikeouts and 5 shutouts. He won 27 games with an ERA+ of 190 and a WHIP. Opposing batters only hit .205 off of him. He had an 8.83 K/9 and a 4.12 K/BB. Seriously, Koufax was amazing. It's a shame he had to call it quits after 1966, though what a year with which to exit.
2. Ted Williams, LF, 1960 (BOS): 2.9 WAR/190 OPS+/95 RC
Williams made the list of top all-time rookie seasons, and here he is with a bookending great final season. He had a relatively pedestrian WAR (not great, not bad), but that's due to his defense, which contributed -1.5 WAR. His oWAR, 4.5, was tied for fourth in the American League, and he also cracked the top of the leaderboards for many of his other offensive statistics. His 190 OPS+ is excellent by any measure, as are his 95 runs created. In fact, he was second in the league in adjusted batting wins, close behind Mickey Mantle. Ted was 42 and unable to competently play the field by the end of the 1960 season, so it's not surprising he chose to call it quits, but he was clearly still a great ballplayer.
3. John Tudor, SP, 1990 (STL): 3.1 WAR/159 ERA+/12-4
Tudor is best known for his dominant 1985, but 1990--his final season--was pretty good too. He retired shortly after the season due to a nagging injury stemming from a previous broken leg, but you'd never know it from his stats that year. His WHIP of 1.025 is very solid for a starting pitcher, as is his 159 ERA+. Tudor started twenty-two games, winning twelve of them (his .750 winning % was third in the NL). Tudor was an all-around very solid pitcher in 1990. Considering how his career was hanging in the balance, and that he only started three games in 1989, that's pretty impressive.
4. Barry Bonds, LF, 2007 (SF): 3.3 WAR/169 OPS+/99 RC
Here's a nice measure of how good Barry Bonds was, even at the age of 42: in 2007 he led the majors in intentional (as well as non-intentional) walks. He was still patient, and still very feared. Those pitchers had good reason to be afraid: he was still one of the greatest hitters in the game. No, he wasn't hitting 73 home runs (perhaps there's a reason for that...?) but 28 is still a very respectable total. The rest of the league had caught up to him--or, rather, he had regressed back to the rest of the league--but still managed to be in the top ten for WPA, adjusting batting runs, and adjusted batting wins. His 99 runs created and 169 OPS+ weren't good enough to make the top of the leaderboards--this was the tail end of the "steroid era," after all--but they're far and away among the best when looking at players' final seasons. Bonds probably could have continue putting up numbers like these as a DH for years to come, but alas it appears he was just too toxic.
5. Will Clark, 1B, 2000 (BAL/STL): 4.1 WAR/144 OPS+/103 RC
Unlike the first four players on this list, Clark's big final season came well after his heyday. Clark was always a consistently above-average player, but his 2000 WAR was his highest since 4.4 in 1992. In 2000, Clark was traded at the trading deadline from Baltimore to St. Louis, whom he helped lead to the National League Championship Series in the wake of Mark McGwire's injury. He did this while killing the ball over the last two months of the season, to say nothing of the whole season. Over all of 2000 he hit .319 with 21 home runs and an OPS+ of 144. His 103 runs created is the most ever by a player in his final season, and his .964 OPS was the highest figure of his career. Clark simply had a very good season, and it's a shame he called it quits after the season, at the age of thirty-six.
6. Billy Wagner, CL, 2010 (ATL): 2.7 WAR/275 ERA+/37 SV
In 2010, his age 38 season, Billy Wagner managed to dominate the National League. He set a career high in ERA (1.43) and had many other figures that rank among his single-season bests: .865 WHIP; 104 strikeouts; 13.5 K/9; 0.6 HR/9; and the three stats featured in the above subject line. He also, despite just having recovered from a year-long injury, threw his most innings since 2006. One year after everybody thought he was finished, Wanger proved that he was still one of the best relief pitchers in the league. Despite all this, he retired after the season (though apparently he has yet to officially file his retirement papers), leaving us to only wonder whether or not he could have kept it up.
7. Mike Mussina, SP, 2008 (NYY): 4.4 WAR/132 ERA+/20-9
Everybody knows that in 2008 Mike Mussina, after eighteen seasons, finally won twenty games in a season and promptly retired. However, while wins are a fairly flawed statistical metric, this was still a very good season by any measure. His 3.37 ERA was sixth in the American League, and his K/BB was a very impressive fourth. He started 34 games, tied for most in the AL, 21 of which were quality starts. This all stacks up very well compared to almost every other final season by a starting pitcher (save, of course, for Koufax's and Tudor's).
8. Dave Nilsson, C, 1999 (MIL): 2.7 WAR/140 OPS+/78 RC
Nilsson, the longtime catcher for the Brewers, had a pretty unheralded (and relatively short, only eight seasons) career. He battled knee trouble throughout his career, and retired from the MLB due to a desire to play baseball in his native Australia. That, however, does not disqualify him from our list, strange though those circumstances may have been. Let's examine Nilsson's 1999: in 115 games he hit .309 with an OPS of .954 and 21 home runs. He also made the All-Star team, though only as a replacement for the Phillies' Mike Lieberthal. Nilsson had a very solid season, and could have had a pretty good rest of his career were it not for his love of his homeland, coupled with his knee troubles.
9. Kirby Puckett, RF, 1995 (MIN): 2.5 WAR/130 OPS+/102 RC
Puckett is the third Hall of Famer (and fifth among those who probably deserve it) to appear on our list. He is another player who had to retire early due to an injury that wasn't slowing down his play, but would cause him problems if he kept playing. 1995 was actually very similar to the previous four or so seasons that Puckett had had, with 1995 having the second lowest WAR among them. That is a bit of a misnomer, however, due to the fact that Puckett lost a whole .9 WAR from his play in the field in 1995. (In 1993, however, Puckett had an oWAR of 3.5 and a dWAR of -3.0. Wow.) Anyway, Puckett's 1995 is only one behind Clark's 2000 for the all-time most runs created in a final season, and his other offensive numbers are similarly competitive. He was among the league leaders in hits (169), doubles (39), and intentional walks (18). He was still one of the best outfielders in the majors and showed no sign of slowing down any time soon. Pity.
10. Larry Jackson, SP, 1968 (PHI): 4.8 WAR/109 ERA+/13-17
The player on our list with the second-highest WAR winds up in tenth place. Oh well. Anyway, Jackson had a very respectable season to close out his unheralded career. (Side-note: Jackson was actually a very good pitcher for the Cardinals in the late 50s/early 60s.) Don't let his sub-.500 winning percentage fool you, though don't be tripped up by his 2.77 ERA either. Jackson had a very good season, that is rendered slightly worse by the fact that 1968 was one of the greatest seasons for pitching in the modern era. Hence a 109 ERA+ with that very low ERA. Still, Jackson had to have done something right to merit a 4.8 WAR, and many of his statistics are perfectly solid, especially for a 39-year-old: 12 complete games, 1.186 WHIP, 0.3 HR/9 (tied for sixth lowest in the NL). This tenth spot was a tough call, but Jackson is well deserving of it.
Runners-up: Britt Burns, SP, 1985 (CHW); Roy Cullenbine, 1B, 1947 (DET); Andy Pettitte, SP, 2010 (NYY); Curt Schilling, SP, 2007 (BOS); Jeff Zimmerman, CL, 2001 (TEX).
