If we're talking about offensive potential to compare who's been the better hitter, I'd say Andrelton has hit about 75% of his offensive potential this year.
Uggla besides homeruns and walks has sucked in almost every other category which IMO has hurt the team more than Andrelton's offensive woes. "Except for that Mrs. Lincoln, how did you like the play". The ONLY thing Simmons has done better offensively than Uggla this year is hit for a better average, which is currently .239. Simmons hits for a little power, but very rarely walks. Here's why walks are important: They aren't an out. They put runners on base, from where they can score. Simmons makes more outs than Uggla does. Outs=bad. Baserunners=good. .
I have no idea how you can say Uggs is having a better year at the plate than Simmons, when Uggla's entire career has been about belting homeruns and driving in runs which he's not doing (yeah he's 7th in the NL, but seems like sans Chris Davis and a few, there's a bit of a slugging power outage this year). It's simple, really, because Uggla has produced more runs than Simmons has, and runs win games--not batting average. And if power numbers are being suppressed this year for everyone else, they have been suppressed for Uggla, too. And he is still 7th in the league in homers, no matter how you spin it
Would you compare Simmons and Freeman's offensive productions as well? Simmons being a premium defensive position, and Freeman playing an offensive position? Maybe not, but both Uggla and Simmons are middle infielders.
If you compare the numbers head to head, sure Uggla's numbers look better. Does that necessarily mean he's had a better year at the plate than Andrelton? I'm not sold on that. What, then, describes a better offensive year, if not which player produces more runs