Heres some situational stats...
Batting 2nd: 25 games, 9 HRS, 25 RBIs, .315 AVG, .342 OBP, .954 OPS
Batting 5th: 40 games, 5 HRS, 27 RBIs, .282 AVG, .335 OBP, .790 OPS
Batting 6th: 38 games, 10 HRS, 25 RBIS, .260 AVG, .308 OBP, .808 OPS
From the second spot, he has the same number of RBIs as batting 5th or 6th (with alot less ABs), a much higher OBP, and an OPS of more than 100 points better. Carlos is obviously on fire hitting 2nd and JM should definately keep him there for the rest of the season.