Cleveland contends that's not the case, but it puts added pressure on pitchers like Zach McAllister to make up for Masterson's absence in the rotation.
Cleveland (53-54) had lost seven of nine heading into Wednesday's contest with Seattle, and earlier in the day it traded Masterson to St. Louis for Double-A outfielder James Ramsey.
Masterson will be a free agent at season's end, and the Indians decided to get a return rather than potentially letting him walk in free agency.
Cleveland also moved out another potential free agent in Cabrera on Thursday, sending him to Washington for shortstop Zach Walters. With top prospect Francisco Lindor at Triple-A Columbus, Cleveland had the flexibility to make the move.
Despite the trades, manager Terry Francona still has hope the Indians can make a second straight playoff appearance.
''We will never raise the white flag,'' Francona said. ''That's not an option.''
Cleveland trails Detroit by 6 1/2 games in the division and Toronto by five for the second-wild card spot after winning 2-0 on Wednesday to keep pace with the Tigers and Blue Jays.
The victory was the Indians' first shutout since blanking Seattle on June 28, and McAllister (3-6, 5.65 ERA) will look to give them another solid performance in this contest.
McAllister went 3-0 with a 2.28 ERA in his first four starts of the season before struggling in May and being sent to the minors. He hasn't been much better since returning to the Indians, giving up six runs in four innings of a 7-5 loss to Kansas City on Saturday to drop to 0-2 with a 4.96 ERA in three July outings.
Since his last victory April 21, the right-hander has gone 0-6 with a 7.65 ERA in nine major league starts.
"If not he's not throwing (secondary pitches) for strikes, they're not going to help," Francona said. "I actually think when he's throwing his fastball and he's locating it, it's a really good pitch. That's what makes Zach the pitcher we need.''
McAllister is 0-2 with a 5.60 ERA in five career starts against Seattle (55-52), which has lost 12 of 18. It fell three games back of Toronto in the wild-card race.
Chris Young will take the mound looking to help the Mariners get on track.
Young (9-6, 3.04) continued his solid run Saturday, allowing two hits and striking out eight in seven scoreless innings of a 4-3 win over Baltimore. He improved to 4-2 with a 2.12 ERA over his last eight outings while holding opponents to a .197 average.
The right-hander has been a pleasant surprise for the Mariners, who picked him up off waivers after he was released by Washington following spring training. Young didn't pitch in the majors last season while dealing with constant shoulder pain.
''I think he's getting stronger,'' manager Lloyd McClendon said. ''We've made a real conscious effort to watch his pitch count and give him a sixth day (off) when we have the opportunity. I think it's paying off.''
Young gave up one run in five innings of a 3-2 win over the Indians on June 27. His only start in Cleveland came in 2005 while with Texas, and he allowed two hits in eight innings of a 3-0 win.