Hard to compare Simpson's and Ballinger's stats, given the latter's injuries over the last 2 years and the former's newness to the league.
That said, I'll give it a go, comparing AB's 2010 season stats (the first with 40 minute games) with Simpson's for this year
MPG - AB 32:46 DS 23:54
PPG - AB 17.6 DS 13.7
Minutes per point scored - AB 1.9 DS 1.7
So Simpson scores faster but is on the court for a helluva lot less time, which we all knew. Simpson 1.7 minutes per point is consistently better than Ballinger's seasonal averages since 2004.
RPG - AB 5.3 DS 8.2
Simpson gets more offensive rebounds per game than Ballinger has in any season since 2004, which includes several seasons with 48 minute games. Simpson's RPG this year is ahead of Ballinger's for every season except 2005, where Ballinger got 9.1 in 48 minute games.
APG - AB 1.1 DS 0.8
Ballinger's assists per game has been ahead of Simpson's for every season since 2004, including the last 2 injury prone seasons.
SPG - AB 0.4 DS 0.8
Simpson's average for this season is roughly double Ballinger's average for each season since 2004.
BPG - AB 1.3 DS 1.7
Ballinger's best here was in 2011, when he got 1.9 per game. After that 2010 is his next best since 2004.
FPG - AB 2.2 DS 2.7
Simpson's foul count would be expected to be about 4 per game if his minutes were increased to the level Ballinger played in 2010.
I believe both players have a good work ethic on the court. Simpson may have a more visible one as, being a younger player, he has more to prove.
Defensively, I don't really know as I haven't seen enough of each with this comparison in mind. However, the fouls per minute comparison suggests Simpson finds himself in poor defensive positions more often per game than Ballinger? On the other hand, he gets a lot more steals and it may just reflect a riskier defensive style. Youth again?
On the stats alone, Simpson is more productive per minute and, being younger, there is a larger upside - if he can get fit enough to play more minutes while maintaining that productivity level. I remain to be convinced he's able to do that. Assuming Ballinger comes back at even 90% of his 2010 performance level, is it worth the risk of losing him in the hope that Simpson's upside can be realised?