Former No. 1 overall pick Justin Upton -- hitting .310 with 13 homers in limited time at Class AA Mobile -- has stunned the baseball world with his sudden appearance in a major league uniform, but now must prove his maturity is on par with his playing skills.
Upton, 19, arrives in Arizona with a reputation for egotism and surliness. More than once during the early part of his career Upton had been observed squabbling with coaches and managers over protocol or lack of hustle, creating a feeling that he might be uncoachable.
But if Upton remains self-absorbed he has managed to hide it more recently, with no major issues reported this year. Still, Upton will be watched closely for issues of attitude.
Upton -- younger brother of Tampa Bay's B.J. Upton -- won his chance to join the Diamondbacks by a combination of circumstances: starting outfielder Carlos Quentin was injured, fourth outfielder Jeff DaVanon failed to find his stroke after coming off the injured list, and -- most importantly -- the Diamondbacks' kiddie corps unexpectedly was found not only to be contending for a playoff berth, but actually leading the pack.
If Upton follows a familiar pattern common among young, inexperience players, he will struggle and be sent back down at least a time or two before establishing himself. But this stunning package of speed and power sooner or later will lay claim to full-time playing status, maybe as quickly as now.