ARLINGTON -- Rangers pitchers John Bannister and Willie Eyre have made considerable progress in their comebacks from Tommy John elbow reconstruction surgery.

Both are pitching so well in the Arizona Fall League that the Rangers deemed it necessary to add both to the 40-man roster on Thursday to protect them from the Rule 5 Draft at the Winter Meetings in Las Vegas next month.

"From what we were hearing, there was a chance we could lose both those guys," Rangers general manager Jon Daniels said.

The Rangers also added infielder Jose Vallejo and pitcher Omar Poveda to the roster and designated pitchers Kameron Loe and Wes Littleton for assignment. Loe is expected to pitch in Japan next year.

Bannister is a 6-foot-4 right-hander who missed the entire 2007 season because of Tommy John surgery. He returned in 2008 and went 4-6 with a 4.15 ERA in 19 games, including nine starts, at Class A Bakersfield, and he went 1-0 with a 4.56 ERA in 11 games, including three starts, at Double-A Frisco.

The Rangers sent him to the Arizona Fall League to pitch for the Surprise Rafters, and he was 0-1 with a 5.00 ERA. In 18 innings, he allowed 19 hits and eight walks while striking out 19.

"He has some of the best stuff coming out of the bullpen out there," Daniels said.

Eyre missed all of 2008 because of Tommy John surgery but was a big part of the Rangers bullpen in 2007, when he was 4-6 with a 5.16 ERA in 33 games and 68 innings. He made eight starts for Surprise in the AFL and was 0-3 with a 6.49 ERA. He could compete for a spot as a middle reliever for the Rangers.

Vallejo is an outstanding defensive player whose primary position is second base, but he could start seeing time at shortstop and third base. He split time between Bakersfield and Frisco and batted .292 in 139 games with 82 runs scored, 42 stolen bases and a .345 on-base percentage. He was the Rangers Defensive Player of the Year in the Minor Leagues but is also starting to make an impact offensively.

Poveda was 4-4 with a 2.97 ERA in 17 starts for Bakersfield, including 3-1 with a 2.38 ERA in his final seven starts after dealing with some physical issues early in the first half of the season.