"They're both available to be down in the bullpen tonight," said manager Eric Wedge. "They've both earned the right to be here."
Outfielder Carlos Peguero was optioned to Tacoma to make room for Thames on the 25-man roster.
General manager Jack Zduriencik said he was in discussions right up to the Deadline, but didn't hear any offers that tempted him after already dealing right fielder Ichiro Suzuki to the Yankees a week earlier and then two of his relievers on Monday.
"If there wasn't a nice match, I wasn't motivated to do something that would take away from where we are currently," Zduriencik said. "We've played decent baseball lately, we have pieces here for the future and in order to make a move it would have to be the right thing to do and I didn't feel in any of my discussions it was the right thing. So we stood pat."
There had been talk of Seattle offering starters Kevin Millwood or Jason Vargas. But Zduriencik said he wanted to keep the Mariners as competitive as possible for the remainder of the season, which meant maintaining a veteran like Millwood even though he'll be a free agent at year's end.
As for Vargas, who remains under team control for another season as he enters his final year of arbitration eligibility, Zduriencik sees the need for an experienced starter to solidify the rotation behind ace Felix Hernandez.
"He's been very effective for us, a very dependable guy," Zduriencik said. "Day in and day out we pretty much know what we have with this kid. He's proven he's a very solid Major League pitcher and we're comfortable with him and I think he's comfortable here. He certainly has a very nice place here with us."
The Mariners are going younger in their bullpen with the departure of League and Delabar, both 29.
Pryor, 23, pitched six games for Seattle in early June before going on the disabled list with a strained groin. He posted a 1.69 ERA (one run in 5 1/3 innings) with four hits, five strikeouts and three walks while showing a fastball in the upper 90s.
Pryor, a fifth-round Draft pick in 2010, was optioned back to Tacoma after recovering from his groin injury. He hasn't allowed an earned run in 20 innings in 16 appearances for the Rainiers this season, allowing 11 hits with 11 walks and 20 strikeouts while recording three saves.
Capps, 21, is another hard-throwing right-hander who was just promoted to Tacoma on Friday after a strong first half at Double-A Jackson. He made his Triple-A debut on Monday, striking out three in 1 1/3 innings of relief. He never imagined that would be his only Rainiers game before getting called up to Seattle.
"It was pretty incredible," Capps said after arriving on a flight from Tucson. "I was pretty shocked for a while. I thought somebody was messing with me at first, but luckily they weren't. This is what you want to play for when you're a little kid. It's definitely a dream come true. This [stadium] is a lot taller than I thought it was. There's a lot of seats in here. You don't really realize when you're watching on TV how big it is. This is nice."
The 6-foot-5, 230-pounder from North Carolina has 19 saves and a 1.23 ERA in 51 1/3 innings combined between Jackson and Tacoma. He led all Southern League relievers in strikeouts per nine innings at 12.96 (72 strikeouts in 50 innings) while at Jackson and has surrendered just two earned runs over his last 37 1/3 innings.
Capps was a third-round supplemental Draft pick last year out of Mt. Olive College in North Carolina.
"He's done a fantastic job in the Minor Leagues," Wedge said. "We felt this was a good opportunity to get him up here. He has a good arm, has some deception with his delivery, just good stuff for a young pitcher."