4 Cardinals spring training heroes who won’t make Opening Day roster

1) Riley O'Brien has made an excellent first impression with the Cardinals

The Cardinals made an under-the-radar trade early this offseason, acquiring Riley O'Brien in a deal with the Mariners for cash considerations. This was more of a roster crunch move for Seattle who opted to not place O'Brien on their 40-man roster. The Cardinals did, and after watching him this spring they're likely glad.

The 29-year-old has just two MLB appearances over the course of his career, none of which came last season. That's a bit surprising since O'Brien was at the top of his game pitching for AAA Tacoma. The right-hander posted a 2.29 ERA in 51 appearances and 55 innings of work, striking out a whopping 86 batters (14.1 K/9).

The Cardinals took a chance on O'Brien and his stuff and so far, have been rewarded for it. He's made five appearances and has thrown five scoreless innings thus far, walking just one batter in those innings.

His impressive spring might earn him a spot on St. Louis' Opening Day roster, but the fact that he can be optioned down to the minors without being subject to waivers makes that far from a guarantee. If he doesn't make it for Opening Day, he certainly will at some point if he continues to pitch well.