The Tyler Greene Fan Club can stop sending the St. Louis Cardinals nasty tweets for the next few weeks: Greene, the Cardinals' perennially toolsy shortstop, has parlayed his outstanding stint in AAA Memphis into a September call-up and the expectation of some significant playing time as the Cardinals attempt to figure out what they have in the 28-year-old. 

Greene, who leads the team in stolen bases with nine despite despite playing all of 51 games, is one of the best baserunners in baseball, a flashy if inconsistent shortstop with an outstanding arm, and a hitter with striking home run power for his size and position. He's also hit a career .213/.303/.306 in 143 MLB games, despite a series of increasingly successful AAA seasons. 

If the Cardinals were still competing it might make sense to keep trotting Rafael Furcal and Skip Schumaker out to the middle infield every day, but they aren't; now's the time to see if Greene is a future starter, a frustratingly talented utility infielder, or nothing at all.