Jeff Kent retired today, from what will probably be a Hall of Fame career. Pre-sabermetric voters will dig his 355 home runs as a second baseman (most all time) and his nine-year prime where he hit 20 HR each season and had 100 RBI in eight of the nine seasons.

He also has the crucial MVP award, because it’s totally not a circular argument for baseball writers to argue someone is great because baseball writers thought he was great.

Viewing Kent with a little more insight, it’s still difficult to argue against him being the best offensive second baseman of his era with a career 123 OPS+.  Weighting on base percentage higher and factoring defense, you might give the edge to Robbie Alomar.  But, it’s certainly close.

There was, however, an interesting Kent comparison in Bill Shaikin’s LA Times article, to Ryne Sandberg.

Kent hit 355 home runs as a second baseman, 74 more than Ryne Sandberg, who was elected to the Hall of Fame in 2005. Kent finished his career with a .290 batting average and 377 home runs; Sandberg finished his with a .285 average and 282 home runs. Sandberg, a 10-time All-Star, also won one National League MVP award.

Shaikin’s implication is clear.  Kent has better numbers than Sandberg.  Sandberg is in the HOF, and, therefore, Kent is hall worthy.  However, Shaikin ignores historical context.

No matter our place on the statistical spectrum, we can all agree on this point.  Sandberg hit his prime in the late 1980s, a lean offensive era.  Kent peaked in the era of juiced balls and balls shriveled by juice.  Their raw performance can’t be pitted on a level playing field.

Had Sandberg played in the late 1990s, he would have had better numbers.  Conversely, had Kent played in the 1980s it would have dampened his performance a bit.  Even if Sandberg and Kent were identical, one would expect Kent to have more home runs.

Adjusted OPS+ addresses this issue, by comparing a player’s performance to the average OPS set at 100.  Hitting 30 home runs 20 years ago was different from doing so now.  How much better than average a player was should be roughly the same.  That stat, though not perfect, should compare across eras palatably, more so than straight raw numbers.

At his peak, Ryne Sandberg had three seasons with an OPS+ of 140 or higher, and three additional seasons above 130 OPS+.  Kent had three seasons above 140 OPS+ and two more above 130.  Kent may still have been better, but the two players seem far closer than Shaikin’s stats suggest.