Be patient with Marte
Scouting and statistics are both important in baseball. While we can argue about the relative importance of each, there is no denying that they both play a role in determining which young players can be productive major leaguers.
Statistics can tell us that Dan Haren, whose ERAs at AAA were 4.93 and 4.15, would be a very good major league starter. Scouting can tell us that Hanley Ramirez, who had a .271/.335/.385 line with 6 homers at AA would be a very good major league shortstop.
Despite cases like these, it is usually true that scouting and statistics often agree on who can become a good or great major leaguer. This makes sense - in general, statistics are a reflection of skills - skills which scouting observes.
Baseball is an odd sport, where raw athleticism and strength or speed do not necessarily translate into "baseball abilities." However, when a minor leaguer has scouting "tools" and accumulates solid statistics as well, this is usually a reflection that his chances of becoming a productive major leaguer are quite high.
Which brings us to Andy Marte. In 2005, Baseball America had the following to say about him: "Marte’s ability to drive the ball to all fields with plus power is outstanding and getting better. He already shows patience at the plate. His glovework is also above average, as managers named him the best defensive third baseman and top infield arm in the Southern League. He oozes intangibles, showing impressive maturity for his age. Marte’s swing has a slight uppercut and can get a little long when he tires, but the Braves consider those minor problems. Still, his strikeout rate jumped in 2004. His trunk has gotten a little thick over the past two years and might need monitoring. His potential as an impact all-around player is unquestioned."
In other words, scouts loved Marte. Even Baseball Prospectus loved him, saying this in 2005: "The best prospect in baseball and a future superstar. As a 20-year-old toiling in the mostly hitter-unfriendly Southern League, Marte hit .269/.364/.525. In only 387 at-bats, he smacked 52 extra-base hits. He's got monstrous power and a broad base of hitting skills. In his prime, expect a few seasons of Adrian Beltre, circa 2004."
But what's more is that Marte's statistics backed up this high assessment of his game. At the tender age of 20, Marte put together a line of .269/.364/.525 with 23 homers in AA. Had Marte gone to college, he'd either be a college sophomore or in his first year of professional baseball; instead, he managed an 889 OPS at AA.
The Braves promoted him to AAA in 2005, and 21-year-old Marte hit .275/.372/.506 with 20 homers in a home park that depressed homers by 25%. He even reduced his strikeouts by 20% without losing any walks or power.
And then Marte was traded. Twice. He went from being one of the best prospects in baseball to a guy that two different organizations decided they didn't want. Of course, fundamentally this changed nothing about Marte; both the Braves and Red Sox had reasons for dealing him that were related more to the team's needs than to Marte himself.
With the Indians, at age 22 Marte went back to AAA. Keep in mind, a 22-year-old in AAA is still quite young. Marte's power declined slightly, and he lost some of his patience, leading to a line of .261/.322/.451 with the Bisons. Marte entered June of 2006 with two homers and 51 strikeouts, and proceeded to hit 13 homers and strike out 30 times in June and July, including a 1.057 OPS in June. He was then called to the Tribe, and underwhelmed for the second time in the majors, hitting .226/.287/.421 in 164 at-bats. On the bright side, Marte did not strike out more than he had in the minors (maintaining a steady rate of strikeing out in about 22% of his at-bats), and amassed 21 extra-base hits in 50 games.
Scouts love Andy Marte. At age 20, Marte posted an 889 OPS at AA. At age 21, Marte posted an 878 OPS at AAA. Yes, he followed it up with a 773 OPS at AAA, and underwhelming performances in the majors. However, Andy Marte is the rare minor leaguer who both scouts and stats love.
It is possible that Marte is simply one of those prospects that miss, for no apparent reason, like Carlos Pena or Ruben Rivera. However, this is very unlikely - and it is WAY TOO SOON to make judgments like that.
23 is the average age of players in AA. If Marte was currently in AA, he'd still be a good prospect. So the fact that he has struggled in the majors is not a terrible sign, especially given his stellar track record against AA and AAA pitching. Additionally, Marte has not been overwhelmed in the majors, as his strikeout rate and high amount of extra base hits attest to.
Scouts love him. Stats love him. This guarantees nothing, but it certainly increases the chances of Marte being a productive player. At age 23, there is still PLENTY OF TIME for him to figure it out. And chances are, he will.