"We're going to find out," manager Ron Washington said.
Feliz was successful in his first three save opportunities after Joakim Soria was traded to the Tigers but let one get away on Sunday afternoon against the Indians at Progressive Field.
Feliz gave up a two-run home run in the bottom of the ninth inning to former teammate David Murphy that erased the Rangers 3-1 lead and the Indians ended up winning in the 12th on a homer by Michael Brantley against rookie reliever Phil Klein.
"We put ourselves in position to win the game and didn't close it out," Washington said. "It's on all of us."
The blown save cost Yu Darvish his 11th victory after he went seven innings, holding the Indians to one run on four hits. He walked two and struck out eight on 101 pitches.
"It's very disappointing that the team lost but there will be days like that," Darvish said. "No pitcher has a 0.00 ERA."
Feliz was 96-100 mph with his fastball before the surgery. On Sunday he was 88-90, which is low even for him after Tommy John.
"I felt great," Feliz said. "The results just weren't what I wanted. I'm not worried about velocity. I'm trying to hit my spots and make sure my mechanics were right."
Feliz, who took over after Neal Cotts set down the side in order in the eighth, started the inning by getting Lonnie Chisenhall on a fly to center. But then he walked pinch-hitter Chris Dickerson after getting ahead 0-2 in the count.
Murphy then hit a first-pitch, 90-mph fastball just over the right-field wall for a two-run home run to tie the game.
"I tried to throw a fastball away and I left it over the middle of the plate," Feliz said.
"It was pretty much the pitch that hopefully every hitter is ready for when it comes," Murphy said. "It was down the middle, a little bit down. I was ready for it."
Feliz has made 11 appearances since being recalled from Triple-A Round Rock and has allowed five runs on eight hits and five walks with five strikeouts. He has a 3.14 ERA and opponents are hitting .167 off him. But he has allowed three home runs in 14 1/3 innings.
"He just didn't make pitches," Washington said. "He didn't make pitches on Dickerson and it cost him. He didn't make a pitch on Murphy and it cost him. There will be days when you see velocity and days when you don't. There will be days when he's 93 to 94 and days when he has to pitch. Today he didn't execute his pitches.
"It's all about executing pitches. You can throw 88-91 if you execute pitches."
The Rangers lost despite taking a 3-0 lead early. The day after going 0-for-9 with runners in scoring position, the Rangers delivered on the first chance they had on Sunday. Elvis Andrus doubled with one out in the first and scored on a single by Alex Rios against Indians starter Trevor Bauer.
In the second inning, the Rangers scored two runs without the benefit of a hit as Bauer started the inning by hitting J.P. Arencibia and walking Leonys Martin and Chris Gimenez. Rougned Odor followed with a flyout to right that scored Arencibia and moved Martin to third. Shin-Soo Choo's fly ball to left brought home Martin.
That was the first time the Rangers have scored multiple runs in an inning without the benefit of a hit since April 19, 2012 against the Tigers.
The Indians scored in the bottom of the second on doubles by Chisenhall and Murphy. That ended a streak of 18 consecutive scoreless innings in day games for Darvish. But he did not allow another hit until a two-out single by Carlos Santana in the sixth.
"I was able to throw my [offspeed pitches] in key situations so it was a very good day," Darvish said. "Murphy had some good swings today and made some pretty good plays in the field so you have to say it was Murphy's day today."
It was also another day to see if the Rangers former closer can do it again. That may be No. 1 on the Rangers' list of priorities as they go through the final two months of the season.
"I'm going to get [Feliz] back out there so he can feel good about himself again," Washington said. "He felt great about himself today, he just didn't get it done. I'm going to give him another chance to get back out there and get it done."