CHICAGO -- The Cubs are exploring a variety of avenues for upgrading their roster before the July 31 Trade Deadline, but the need for an impact lefty in the bullpen remains the most glaring. That was evident through the prism of one transaction prior to Friday's game against the Padres at Wrigley Field.

Chicago activated right-hander Carl Edwards Jr. from the 10-day injured list -- following his bout with a left thoracic strain -- and optioned left-hander Randy Rosario to Triple-A Iowa. The return of Edwards gave the Cubs seven righty relievers in the bullpen, with Kyle Ryan serving as the lone left-handed option for manager Joe Maddon.

"Rosie was just here and did OK. Kyle's been outstanding," Maddon said. "It's always nice to have more than one -- I can't deny that. But again, when Carl is right, he's able to mitigate all that."

To Maddon's point, Edwards has held left-handed batters to a .171 average and .535 OPS over the course of his career, and limited them to a .154/.200/.154 slash line in the 15 appearances prior to landing on the IL. During that stretch of games between May and June, Edwards had a 2.03 ERA with 15 strikeouts, four hits allowed and three walks issued in 13 1/3 innings.

The Cubs traded lefty Mike Montgomery to the Royals on Monday night in order to acquire catcher Martin Maldonado. Montgomery was more of a mult-inning reliever with Chicago, and Ryan -- a ground-ball specialist -- does not really fit the mold of a pure left-on-left pitcher. Entering Friday, lefty batters had turned in a .341/.401/.556 slash line against Chicago's southpaw relievers this year.

Besides Edwards, the Cubs do have an assortment of righties who have fared well against lefties this year. Brandon Kintzler had held lefty batters to a .144 wOBA and .200 slugging percentage in 2019, entering Friday. Sidearmer Steve Cishek (.305 wOBA and .344 SLG) had also done well, along with setup man Pedro Strop (.264 wOBA and .333 SLG).

Still, expect Chicago to target a lefty ahead of the Trade Deadline, especially given that there are no more trades in August.

"When you get to the end of the year," Maddon said, "and you get a real left-handed heavy lineup, it helps [to have a second left-hander]."

Edwards made four Minor League rehab appearances for Iowa before being activated, and he said he has not experienced any soreness while playing catch the day after his most recent outings. That helped convince the Cubs to add Edwards back into fold now -- a dozen days before the Deadline.

"It's just about Carl getting assertive and aggressive and letting it fly, not overthinking it," Maddon said. "That's primarily what I just want to see him do. Just go out and pitch. Stop worrying and thinking about too many items. See the catcher's glove and just throw it."

Worth noting

• In the wake of Thursday's team off-day, the Cubs plan on keeping their rotation in order rather than shuffling things around. For the upcoming road series against the Giants, Chicago plans on handing the ball to Alec Mills (Monday), Yu Darvish (Tuesday) and Jon Lester (Wednesday).

• Left-hander Cole Hamels (10-day IL, left oblique strain) was scheduled to play light catch on Friday and will throw off a mound again on either Saturday or Sunday. Barring any setbacks, the next step would likely be a simulated game or Minor League rehab outing.

• Maddon said Cubs catcher Willson Contreras (10-day IL, right foot strain) was progressing well. Contreras was slated to resume baseball activities this weekend.

• Cubs pitching prospect Adbert Alzolay (ranked No. 4 on the Cubs' Top 30 list by MLB Pipeline) left his Triple-A start on Wednesday night after 3 2/3 innings due to right biceps inflammation and went on the Minor League injured list.