IF he stays healthy, he posts very nice numbers, esp. considering where you can draft him. Never a major HR guy, but his runs should top 100, 25-30 SBs conservatively, 280+ avg. The only real question is his health and durability.
And as to pre/post AS break sb counts...that is not unusual as players tire out and wear down after a long season...or try not to get themselves needlessly hurt in a meaningless Sept game depending on the race of course. Bottom line is 25+ SBs is 25+Sbs and if you think he will tail off in the second half you, then deal him. From what I saw of him last season, he did quite well the last month of the season, though the sb count did drop. Still hit for a good avg and scored runs...a very nice late round pick, IMO.