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7/4/2014 11:51 P.M. ET

Hart activated from 15-day disabled list

Mariners designate Gillespie for assignment

CHICAGO -- Veteran designated hitter Corey Hart was activated off the 15-day disabled list by the Mariners and immediately penciled in at cleanup hitter for Friday night's game against the White Sox, with outfielder Cole Gillespie designated for assignment to make room on the 25-man roster.

After missing the past seven weeks with a strained left hamstring, the 10-year veteran said he's eager to get back with a Seattle club that has been one of the hottest teams in the Majors for the past month.

"It's exciting," Hart said prior to Friday's game. "Any time you get called up, whether it's from rehab or for the first time, it's a good day. It's always fun to be in the big leagues. The team is playing well, so I'm excited to be back on a team that is obviously competing and playing well."

Hart, 32, hit .297 with three doubles, one triple, one home run and four RBIs in 10 rehab starts with Triple-A Tacoma. The two-time National League All-Star hit .209 with five home runs and 17 RBIs for Seattle before hurting his hamstring while stealing a base in Minnesota on May 18.

Hart signed a one-year deal as a free agent with Seattle after missing all of 2013 with the Brewers following a pair of microfracture knee surgeries. He gives the Mariners a needed right-handed presence in the middle of their predominantly left-handed-hitting lineup, an important factor with tough southpaws Chris Sale and Jose Quintana on the hill the next two nights for the White Sox.

"He's swinging the bat good, he's a force in your lineup. It just made sense to bring him back," said manager Lloyd McClendon. "To have a righty just to have a righty doesn't mean anything. You need a righty that can swing the bat. Corey can swing the bat. It's nice to have him and hopefully he'll have a very productive series here."

Veteran outfielder Endy Chavez has been filling most of the DH duties recently, so Hart provides a power boost there and can also play outfield and first base if needed.

With Gillespie's departure and the recent demotion of Stefen Romero, the Mariners are down to four regular outfielders in Dustin Ackley, James Jones, Michael Saunders and Chavez. But utility man Willie Bloomquist can play the outfield and Hart played a game there Wednesday in Tacoma just to show he's capable of returning to his former position as needed.

"It was nice to get out there," Hart said. "I haven't done it a lot, so it was more nerve-wracking than anything. But I'm able to do that, so if that's something they need, I won't win any awards out there, but I'll catch it if it's my way."

Gillespie, 30, hit .254 with one home run, five RBIs and nine runs scored in 71 at-bats over 34 games since being called up in late April. The Mariners have 10 days now to trade, release or outright Gillespie's contract to the Minor Leagues.

Gillespie was designated for assignment because he's out of Minor League options. If he clears waivers this weekend, he'll then have the choice of opting for free agency or re-signing a Minor League deal with the Mariners.

Smoak comes off DL, assigned to Tacoma

CHICAGO -- The Mariners activated first baseman Justin Smoak off the 15-day disabled list on Friday and optioned him to Triple-A Tacoma, which means Logan Morrison will remain the club's first baseman even now that Smoak is done with his rehab assignment.

Smoak, 27, has been Seattle's starting first baseman since being acquired from the Rangers at the trade deadline in 2010, but the Mariners will stick with Morrison as he's hit .267 with four home runs and 14 RBIs since coming off the disabled list himself on June 10.

"It's tough, but we only have so many spots," said manager Lloyd McClendon. "LoMo has been playing extremely well and has been a big lift for us and Smoaky will continue to get at-bats there and get sharp. Listen, at some point he'll be helping this club again."

Smoak went on the 15-day disabled list on June 10 with a strained left quad muscle. He hit .204 (10-for-49) with five walks, three doubles, one home run and three RBIs in 13 rehab games. Position players can only stay on a Minor League rehab for 20 days, so the club would have needed to make a decision on Smoak by Tuesday.

Since Smoak had a Minor League option remaining, the choice was made Friday to option him to Tacoma so he can keep playing.

"He just needs to work on his skills," McClendon said. "He's a Major League player. He just has to bide his time there, stay healthy, get some at-bats and swing the bat good."

Smoak got off to a good start this season, but struggled for the month before going on the DL and was hitting .208 with 12 doubles, seven homers and 29 RBIs in 63 games. He's batted .225 with 74 home runs and 233 RBIs in five seasons in the Majors.

Paxton feels good in 'pen, sim game next

CHICAGO -- Mariners rookie left-hander James Paxton threw his third bullpen session since beginning his latest comeback Friday at U.S. Cellular Field and now will progress to a simulated-game situation against live hitting on Tuesday when the club returns to Seattle.

Paxton said he threw 52 pitches, slightly more than scheduled because he was feeling so good.

"I was actually supposed to throw 45, then we did some [pretend] hitters at the end," said the 25-year-old southpaw. "I was feeling really good, so they said do three hitters. I did and everything was great. It felt really good. I was loose, threw all my pitches today and everything felt good."

The youngster went on the disabled list after his second start of the season on April 8 with a strained lat muscle in his left shoulder, then had to be shut down again after making one rehab start in late May. Though no radar gun was used Friday, Paxton said his velocity felt fine as he let loose with his fastball.

"I'm really bad at telling how hard I'm throwing, but it was coming out real easy," he said. "I wasn't trying to throw hard, it was just popping out of my hand and making a good sound when it hit the mitt. So it felt like I was coming in pretty good."

Paxton said he even threw some curves as he worked through his repertoire.

"It was pretty good, a little loopy," he said. "But in bullpens, it usually is. You don't usually get that sharp one until you get some adrenaline going with hitters in the box. I'm not really worried about that. Just looking forward to the next step."

And that step will come Tuesday when Paxton takes the mound against some Mariners hitters. He'll get another sim game or more before being sent out on another Minor League rehab stint, likely after the All-Star break. Paxton was 2-0 with a 2.25 ERA in his first two starts this year and is 5-0 with a 1.75 ERA in six starts since his Major League debut last September.

Worth noting

• With the Yankees' Masahiro Tanaka giving up four runs in his latest win Thursday, Felix Hernandez now leads the AL in ERA at 2.10. Going into Friday's games, he's also first in WHIP (0.919), tied for first in quality starts (16), second in innings pitched (128 1/3), third in strikeouts (137) and tied for third in wins (10).

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.