"You're always searching for the best fit, to where you feel like you have someone that's going to be the guy that closes games for you, so that everybody leading up to that has an understanding of when guys are going to pitch. We're just not there yet, unfortunately. Jim has really made some big strides for us, but we're just not all the way there with him yet. So it's still going to probably be a matchup-type situation."
After stringing together 10 straight scoreless appearances in innings not named the ninth, Johnson appeared ready to resume the only job he knew in the previous two seasons. But he's since given up six runs over his last four outings, including one in a save situation against the White Sox on Monday.
Lefty Sean Doolittle was quickly brought in to secure the win, bringing to question his ability to serve as the full-time closer.
"[Doolittle] certainly has the stuff to do it, but there are times when he's so good coming in with guys on base, whether it's the seventh or eighth inning, and sometimes those are the most important leverage situations of the game," said Melvin. "That's a difficult part in waiting for the ninth inning for him.
"One of the reasons the organization signed him long term is him potentially filling that role. We'll see how it goes."
Of the success Johnson's had this year, most has come on the road, where he has a 2.00 ERA and .194 opponents' average. The numbers balloon at home (8.59 ERA, .194 opponents' mark), and as a result, he's been hearing plenty of boos.
"When you do come from another team and you're with another organization, a fan base like ours, you do want to go out there and show them what you have," said Melvin. "I think he's a pretty tough guy, to where at some point in time, hopefully, that's not an issue for him.
Jane Lee is a reporter for MLB.com. Read her blog, Major Lee-ague, and follow her on Twitter @JaneMLB. This story was not subject to the approval of Major League Baseball or its clubs.