Jim Thome or Richie Sexson?

Part of the debate on whether to trade or re-sign Adam Dunn is that we know what he is now, but what will he be in the future?

Will Dunn contunue to slug 40 homers and draw close to 100 walks a year?  Will his defense, which has been bad this season, but not historically bad, stay roughly the same or get even worse as the years advance?

Will he finally decide that a move to the A.L. would increase his value to a team?  Or will he stubbornly hold to his belief that he's a complete player and insist to stay in the National League.

Dunn has been an incredibly gifted offensive player for his entire career.  He came up as an outfielder and moved to first base last season.  He's never posted an OPS+ lower than 114, and his career 162-game average is 133.  For 2010 -- at age 30 -- he sits at 151, which would be his finest OPS+ season of his career.

Sounds an awful lot like a couple of other players in MLB history. 

Jim Thome came up a a third baseman, made the transition to first base relatively early in his career, and has been primarily a DH for the last five seasons.  He is one of the elite power hitters of our generation.  Until his age 37 season, he never put up an OPS+ under 126 in a non-injury year.

In his age 30 season with the Indians, he put up -- to that point -- a career high 170 OPS+. 

What happened to Thome? 

The next season, at age 31 was even better, leading the Majors with an astounding 197 OPS+.  Remember, this was 2002.  Anyway, in 2003 at age 32 he signed his big free agent contract and put up OPS+ of 144, 85 (he was injured most of the year), 155, 150, 123 and 118 last season.  This year, at age 39, he continues to be a valuable member of a competitive team posting a 150 OPS+ in 192 at bats for the Twins.

Richie Sexson came up an outfielder and gradually transitioned to first base.  He didn't put up quite as gaudy OPS+ numbers as Dunn or Thome, but in 12 seasons he averaged 122.  His career high OPS+ was 144 in 2005 -- at age 30. 

After his age 30 season, the Seattle Mariners re-signed the big guy (6'6") to a new contract that paid him $44 million the next three years.

What happened to Sexson? 

At age 31 he had a decent, but not stellar 117 OPS+.  At age 32 it dropped to 84, and at age 33 went to 88.  His last four years his homers dropped from 39 to 34 to 21 to 12.  The Mariners released Sexson in July of 2008 and was signed by the Yankees a week later.  He appeared in just 22 games for New York before he was released.  He never played again.

I'm not equating Dunn, Sexson and Thome.  But looking at their statistics, they certainly followed the same career arcs up to their respective age 30 seasons carrying the same skill set:  power hitter, patient at the plate, defensively limited and transitioned to first base.

The difference is what happened next.  Will Adam Dunn be able to follow the career arc of Jim Thome and be included in the list of the finest power hitters of our generation?  Or could Dunn's skills erode as quickly as Sexson's?

We don't know the answers to those questions, but Mike Rizzo has to make an educated decision in the next ten days.

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