After Butler was sent down earlier in the year to hone his breaking pitches, the Rockies right-hander has struggled since being recalled on July 19 to fill an open rotation spot. Over his last five starts, Butler is 0-4 with an 8.28 ERA and has surrendered at least four earned runs in each of his last three outings.
"He's just not commanding much," Rockies manager Walt Weiss said before Friday's series opener with the Padres. "Pitches are either running out of the strike zone or running back over the middle of the plate elevated. We see glimpses of him being good, but it's just not been consistent.
"He's got some things that he knows he needs to work on, and that's what he's going to do."
Weiss said Butler's bullpen sessions have been "as impressive as anybody," but not much has translated to the field. In addition to simply more command of all his pitches, the Rockies specifically want to see more sink with his two-seam fastball.
"We're trying to get it sink more than run, to be honest with you, Weiss said. "It does run a lot, but when pitches run, they stay on one plane. You want to see some depth to that two-seamer."
Meanwhile, Logan, who pitched through elbow problems all last season and eventually had elbow surgery to remove a bone spur last September, has struggled for much of this season. Originally signed to a three-year, $16.5 million deal in December 2013, Logan hasn't been the late-inning rock the Rockies envisioned.
He's been reduced to more of a specialist reliever, having thrown less than one inning in 21 of his last 22 appearances. Logan's last two outings were particularly poor -- both of which were magnified in battles with Mets outfielder Curtis Granderson.
Logan faced him with the bases loaded on both Monday and Tuesday, first hitting Granderson with a slider and then walking him the next day on the same pitch.
"Even with this thing, going, I was finishing my sliders pretty good up to the last couple outings," said Logan, who added that he fought the DL stint before finally conceding. "It's just part of it. I've felt better this year than I have a lot of years. I feel better and stronger, and everything is coming out good.
"But I take all the credit for my numbers this year. You're never going to be 100 percent again -- if it's a mental thing or a physical thing. I just turned 31, so my body is not getting any younger."