"That was obviously a tough decision," manager Jeff Banister said before Friday's game against the Royals. "A very challenging decision based on the body of work from last year. Obviously early on, he had some challenges. He was working his way back and was the closer, but there are still some execution of pitches [Tolleson] needs to work on."
Tolleson appeared in 73 games for the Rangers in 2015 -- going 6-4 with a 2.99 ERA, a 1.15 WHIP and 35 saves. He began this season as the closer, but lost the job in May after four blown saves and a 9.28 ERA through his first 18 games.
"It stinks. ... I'd rather be here with this team," Tolleson said. "I wasn't shocked by it. I knew they needed to make room and I was the last guy out of the bullpen. I know how it works. I haven't been throwing well all season. That's it. I understand the decision."
Tolleson's struggles can be defined by his changeup, which was his best pitch in 2015. During that season, Tolleson got opponents to swing and miss at 33.3 percent of his changeups. That was down to 17.6 this season.
"For me, the important thing is to improve my worth," Tolleson said. "In the past I have shown I can be effective and do a good job. I am going to spend the next month proving that so I can be up here sooner than later."
The Rangers optioned Tolleson because they wanted three left-handers in the bullpen: Jake Diekman, Alex Claudio and newly-acquired Dario Alvarez. Texas will stay with four right-handers -- Sam Dyson, Keone Kela, Matt Bush and Tony Barnette -- and a seven-man bullpen.
The Rangers have had an eight-man bullpen this season, but Banister wants a four-man bench that includes utility infielder Hanser Alberto. His presence allows Jurickson Profar to play in the outfield and he started there on Friday night.
"We weren't willing to go short on the bench," Banister said.
• Designated hitter Prince Fielder underwent surgery to repair a herniated disk in his neck on Friday and the operation went as expected. Fielder, who is out for the season, will be in a neck brace for two weeks and then will be re-evaluated.
• Cole Hamels is 12-2 after Thursday's win over the Royals. He is the first Rangers pitcher to ever have 12 wins and fewer than four losses before the end of July.
• Outfielder Shin-Soo Choo, on the disabled list with inflammation in his lower back, is eligible to be activated on Thursday. The Rangers are still concerned about how effective he'll be down the stretch and have inquired about offensive help in some of their trade talks. They touched base with the Yankees about outfielder Carlos Beltran although it doesn't appear to be a serious discussion.