Baseball's active rosters expanded to 40 on Tuesday, and we saw the first wave of call-ups, with more likely to come as minor league seasons and postseasons end in the next few weeks. Here's a look at five prospects called up Tuesday who are worth your attention:Michael Brantley, CF, Cleveland: Brantley has great bat speed combined with outstanding bat control, which is how you can go 2,161 plate appearances in the minors with more walks (258) than strikeouts (190). He's also a plus runner and can play center field, although that position is occupied in Cleveland by Grady Sizemore at the moment. Brantley has below-average power, so playing in an outfield corner might be a stretch, although I think he'll hit for enough average to make it work. If the Indians choose to shut Sizemore down at any point this month (he might have elbow surgery before year's end), they could give Brantley an extended trial in center. Tyler Flowers, C, Chicago White Sox: Flowers is patient and hits for power, but he's rough behind the plate and probably will rack up the strikeouts in the majors. Trading Thome gives the White Sox the chance to get Flowers some at-bats this month without having to add to his catching workload for the season, allowing him to concentrate on hitting rather than forcing him to learn all the pitchers while he's trying to adjust to big league breaking balls. If he stays behind the plate long term, which I think he can, he's a very good prospect because of his offensive potential. Carlos Carrasco, RHP, Cleveland: Carrasco had a rather forgettable major league debut Tuesday night, giving up three home runs and allowing nine other baserunners in three innings. He came over to Cleveland in the Cliff Lee deal after a few years atop Phillies prospect lists, with a solid-average fastball and changeup but a below-average breaking ball and questions about his toughness and feel for pitching that aren't going to go away after that first outing. Neil Walker, 3B, Pittsburgh: I've never been a big Walker fan -- he doesn't control the strike zone, his swing gets long and he can't play third base -- but there is no reason for the Pirates to leave him to rot in Triple-A when they're playing other young players all over the field. Walker hit .264/.311/.480 repeating Triple-A this year and, at 23, could still improve his power output or his plate discipline. He probably never will have the bat to play first base, but the Pirates aren't brimming with alternatives, and at this point any value they extract from Walker -- who was drafted by the previous regime, in part because he's a local kid -- is found money.Josh Thole, C, New York Mets: Thole, like Flowers, doesn't grade out well in terms of tools or athleticism, but he has a history of performance --- in Thole's case, one that improves when he's promoted, which is about as good a sign in a player's statistical record as you'll find. Thole differs from Flowers in his approach at the plate, as Thole is more about bat control and contact instead of Flowers' raw power, and, as a result, Thole hit .328/.395/.422 in the Double-A Eastern League this year at age 22. The Mets have received no offense from behind the plate this year and have to be worried about who'll catch for them in 2010 and beyond, so giving Thole a brief look this month is just good sense.