The Cardinals took Adams in the 23rd round of the 2009 draft, not usually the sign of a prospect, at least not for a college hitter. But Adams did good work in the minors, including batting a remarkable .340/.375/.603 for Class AAA Memphis this season. The Cardinals called him up when Lance Berkman got hurt, and he's now played their last two games at first base.
Here's SB Nation St. Louis' take on what to expect from Adams:
Matt Adams is listed at 6'3", 230, which is almost certainly not correct. He's not Prince Fielder, and he gets good marks for athleticism, but he is a big, big man and will not be playing the outfield. He can hit the ball really hard, but he's interesting because he can also hit the ball really frequently ...
His walk rate means it's hard to see him as a future All-Star with his current skill-set, but he could well be an average—and very exciting—first baseman in the very near future.
The Cardinals don't return to PNC Park until late August, so it'll be awhile before Adams makes his Pittsburgh debut. It will be interesting to see if his lack of walks gets him in trouble before then, but in the meantime, there are a lot of teams, presumably including the Pirates, that could use him right now.