The Race for Round Rock kicks off with the C1 position in question. USA Today has an interesting note on how Mills will decide:
Houston manager Brad Mills will watch the duo closely, comparing everything from their hitting stances to their arm strength to the way they talk with pitchers. While Towles has the edge in experience, Castro arrives with the label as one of the franchise's most coveted prospects.
We didn't come out here to play tiddlywinks, son.
-Hal Smith
