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7/30/2014 6:25 P.M. ET

Paxton throws 'pen session, readies for rotation return

CLEVELAND -- Rookie left-hander James Paxton threw a 45-pitch bullpen session on Wednesday at Progressive Field and appears poised to rejoin the Mariners to fill a rotation opening Saturday at Baltimore.

The Mariners currently only have four starters on their 25-man roster, but Paxton is traveling with the team after making his third Minor League rehab start on Sunday with Triple-A Tacoma. Manager Lloyd McClendon is waiting to see how Paxton bounces back after his normal between-start throwing session Wednesday, but all signs point to the 25-year-old getting the nod.

"In my mind, I'm ready to compete," Paxton said when asked if he was prepared to start Saturday.

The 6-foot-5 southpaw has been on the disabled list since April 8 after straining the lat muscle behind his left shoulder during his second start of the season against the Angels. Paxton won that game and is 2-0 with a 2.25 ERA this season and 5-0 with a 1.75 ERA in six Major League starts since his debut last September.

After being shut down in late May following his initial rehab start, Paxton is pleased that everything is progressing smoothly this time.

"I was throwing all my pitches where I wanted to throw them today, my mechanics felt smooth, everything was coming out at the right time. It felt good," he said. "It's a good feeling. I've been waiting a long time. To be able go out there and throw as hard as I want and not have any pain at all or any tightness the next day, it feels really good."

Paxton is surprised his return has taken this long, but has maintained a positive approach throughout.

"Honestly, I thought it would be a shorter rehab then it ended up being," he said. "I had that little setback there that took some time. But I'm just happy to be back where I am now and feeling normal again."

Iwakuma in control with mastery of command

CLEVELAND -- When Hisashi Iwakuma walked Michael Brantley on four pitches in the first inning of Tuesday's 5-2 victory over the Indians, no one was more surprised than Mariners catcher Mike Zunino.

"That's what got me," Zunino said after Iwakuma issued his first walk in a month, stretching over 35 2/3 innings. "It was on four pitches. I was like, 'Man!' It's one of those things that happens, but it doesn't happen very often."

So Iwakuma is human after all?

"I didn't think so until then," Zunino said with a smile.

The 33-year-old right-hander has 94 strikeouts with just nine walks in his 17 starts this season. That strikeout-to-walk ratio of 10.44 is the best in the Majors among starting pitchers, and Iwakuma also has been the most efficient starter in baseball with just 13.5 pitches per inning, while ranking third in the American League in WHIP at 0.99.

All that is impressive. But what's even more impressive is that even though opposing hitters know Iwakuma is going to efficiently throw strikes, they aren't able to zero in on his offerings with any frequency.

"His splitter is exceptional," manager Lloyd McClendon said. "At the start of the season, he didn't have a real good command of the fastball or velocity. But now he can through that fastball to four different quadrants of the strike zone, he's got a little cutter to go with it and mix in his slider, curveball. He throws a lot of strikes, but he gives you a lot of different looks."

Zunino joked that Iwakuma's rare walk was designed to let hitters know he will indeed go outside the strike zone on occasion. But the young catcher also marvels at how well the veteran is able to keep people off balance even while throwing so many strikes.

"I think it's his ability to change speeds and keep the ball down in the zone," said Zunino. "Some guys will stay in the zone, but then one pitch will be a mistake up in the zone. He's just so good at keeping the ball down. He pitches to contact, but knows how to do it well. Keep it down or just under the zone so guys can only see the top of the ball and either chop it or slice under it and he gets a lot of weak pop flies."

Mariners' brass busy with Deadline approaching

CLEVELAND ---As Thursday's 1 p.m. PT non-waiver Trade Deadline approaches, the Mariners remain in conversations on multiple fronts as general manager Jack Zduriencik looks at available options to help his club contend for a playoff berth.

The Mariners have most of their top baseball people in Cleveland, where Zduriencik and his staff are working the phones and waiting to see what possibilities shake out in the final hours.

Zduriencik and assistant general manager Jeff Kingston are with the team, along with pro scouting director Tom Allison, Minor League director Chris Gwynn and amateur scouting director Tom McNamara.

Zduriencik has been talking to GMs around the league for the past few months to set the stage for potential Trade Deadline deals and the Mariners have been linked to numerous players. The most likely addition would be a right-handed-hitting outfielder, given the team's need for offense and a balance to the lefty-leaning lineup manager Lloyd McClendon has been using most of the season.

Thus, veterans like Marlon Byrd (Phillies), Dayan Viciedo (White Sox), Drew Stubbs (Rockies), Alex Rios (Rangers), Chris Denorfia (Padres) and Justin Ruggiano (Cubs) have been mentioned as possibilities, along with the higher-priced Matt Kemp of the Dodgers. Cubs utility man Emilio Bonifacio was the latest name to emerge, as the 29-year-old can play center field as well as shortstop or second base.

It seems less likely that the Mariners would give up prospects to improve a pitching staff that already leads the American League in earned run average. The Mariners have made one trade so far, acquiring designated hitter Kendrys Morales from the Twins for reliever Stephen Pryor last week, with the hope of improving an offense that ranks near the bottom of the league in most statistical categories despite the club's 55-51 record going into Wednesday's game.

McClendon has been involved with the talks with Zduriencik and his staff, but insists he's not getting too caught up in that.

"I'm focused on what I've got," McClendon said. "That's the only way you can operate."

Worth noting

Brad Miller was back at shortstop on Wednesday after Chris Taylor got the start Tuesday and went 1-for-4 with an RBI double. McClendon had said all along that Miller would get the start Wednesday against tough right-hander Corey Kluber and that Taylor's hand was fine after he got hit by a pitch on Tuesday.

• Right fielder Michael Saunders took batting practice for a second day in a row on Wednesday as he continues his return from a strained oblique muscle. McClendon said Saunders wasn't swinging 100 percent yet and that "it's going to take some time," but the manager said he remains hopeful that the 27-year-old will be able to go out on a Minor League rehab stint by this weekend.

• Top pitching prospect Taijuan Walker gave up three home runs in Tacoma's 5-3 loss at Las Vegas on Tuesday. The 21-year-old allowed four runs on six hits with two walks and seven strikeouts in a five-inning outing. He's 4-2 with a 4.14 ERA in nine starts for the Triple-A club.

Greg Johns is a reporter for MLB.com. Follow him on Twitter @GregJohnsMLB as well as his Mariners Musings blog. This story was not subject to the approval of Major League Baseball or its clubs.