RHP Jumbo Diaz was optioned to Triple-A Louisville on Tuesday after posting a 5.40 with four earned runs and three homers allowed in 6 2/3 innings. Diaz, 32, has seen a drop in velocity this year, but manager Bryan Price insists that's not his issue. "It's pitch execution and pitch usage," Price said. "You can no longer get by with just velocity. You can't use this level as a testing ground for an extended period of time."

Diaz was recalled from Triple-A Louisville on Friday, C. Trent Rosecrans of the Cincinnati Enquirer reports.

Diaz will return to the Reds for the first time since being optioned on June 7. The right-hander has struggled in 25 big league appearances this season, posting a 6.65 ERA across 23.0 total innings. He's been sharp at Triple-A, however, allowing just two earned runs over 16.0 innings (13 appearances). In a corresponding move, the Reds optioned right-hander Carlos Contreras to Louisville.

Diaz was optioned to Triple-A Louisville on Sunday.

Diaz has allowed four earned runs in his last three appearances, and has now appeared on back-to-back days, throwing 38 total pitches. The 6-4 right-hander already has a loss and a blown save to his name in June, but the need for a fresh arm in the bullpen likely played a more significant role in this decision than the actual performance of Diaz. He should be back with the major league club at some point down the road, though a 6.65 ERA suggests he won't see much more than middle relief.

Tasked with protecting a two-run lead in the eight inning, Diaz served up a two-run home run to Jorge Soler, taking a blown save Monday.

After a strong start to his season, Diaz has now allowed a home run and two runs in each of the past two days. Diaz could re-find his form moving forward, but he could lose his role in the eighth inning after his last two outings.

Diaz is a candidate to pitch the eighth inning going forward, manager Bryan Price said before Wednesday's game.

Diaz had a big strikeout after Kevin Gregg did the damage in the eighth inning Monday. "Yeah, came in and got the strikeout, and that was big," Price said. "He's another guy that doesn't have the major league experience that Kevin has. He certainly has the power arm and I think he may be a guy that's comfortable in some of those late inning situations."

Diaz is expected to win a roster spot for Opening Day after pitching well after his callup last year.

In fact, there's a reasonably good chance that Diaz will be one of the top setup men for Aroldis Chapman, though he's not guaranteed that slot. "We're counting on him," Reds manager Bryan Price said. "Again, there are no freebies here. We still need guys to come in and they have to look ready to help us in spring training."

Diaz's got the loss Friday night against the Brewers, allowing a run in a tie game in the ninth inning while retiring just one batter. He allowed two hits and two walks.

While one of the walks was intentional, Diaz's control abandoned him even accounting for the free pass, with just four of his 14 pitches going for strikes.

Diaz picked up his sixth hold of the season Sunday, striking out the two batters he faced after entering the game with two runners on.

Jumbo now has a sterling 26:7 K:BB (two of those walks were intentional) in 23 innings since getting the call, and now is getting into the game in more important situations. He's the Reds' third most reliable reliever behind Aroldis Chapman and Jonathan Broxton.

The Reds are becoming increasingly comfortable using Diaz in important situations late in the game.

With J.J. Hoover continuing to struggle and Logan Ondrusek on the DL, the Reds needed another reliever to emerge as a reliable seventh inning option whenever Sam LeCure isn't available.