Mark Appel
Mark Appel's fall appearance is helping to erase the memory of the disastrous 2014 season. He pitched well in AA after his promotion, and so far in Arizona has been close to dominant. In two starts, he has pitched 7 innings, allowing only 2 hits and three walks compared to 8 strikeouts. He has yet to allow a run. Keith Law (insider) wrote up his first outing, and noted his velocity and slider were good, but he was lacking fastball command.
Andrew Aplin
Aplin has been pretty clearly the MVP of the Rafters so far, batting .500/.500/.857 in 14 at bats. His biggest game came on October 10, in a 12-2 walloping of Peoria. The Rafters scored 11 runs in the 5th inning in that game, and Aplin was 2-2 with a grand slam in that inning alone. He that day 4-5. He also drove in the only run of the night last night, with a triple in the 8th.
Rio Ruiz
Ruiz has struggled a bit in the early going, batting only .217/.308/.268 in in 23 ABs, although he went 2-2 with a walk last night. Law (insider) commented on some extra weight and a resulting slower bat speed.
The remainder of the Astros have received minimal playing time. Velasquez has only pitched in 1 inning, and gave up two hits and a walk, but avoided any runs by striking out 2. Mitch Lambson and Tyson Perez have both pitched 4 innings, with a Lambson home run the only run allowed between them. Perez earned the save last night. Tyler Heineman has gone 2-5 with two walks and Joe Sclafani is 0-3 so far.
For more on the Astros in the Arizona Fall League, go read these first hand account of a very Astros-Centric game last night over at What the Heck, Bobby?