Slaten threw a simulated game on the back practice fields at Tucson Electric Park on Sunday, throwing about 24 pitches to Minor League hitters. He faced right-handers and left-handers and used all his pitches. He even fielded a ball hit back to the mound, giving him a taste of pitchers fielding practice.
"It's kind of the next step for him," manager Bob Melvin said of the simulated game. "I'm really encouraged about him potentially starting [the season] with us. More so than the other guys."
Though Melvin wasn't ready to start speculating on a target date for Randy Johnson to join the roster in the regular season, he has been encouraged by Johnson's smooth progression through recovery so far, including his start on Saturday, when he threw 43 pitches in three innings and allowed only one hit. Johnson is working his way back from back surgery.
"It's been great," Melvin said of Johnson's progress. "We're backing off to the point where we're just thinking about health. That's the most important thing, and he knows to alter from his routine if he has to. We haven't run into any snafus yet. If we get a day where he's a little sorer than normal, we'll just back off a day. If we have to bump him back a day or bump back his bullpen or a start, we'll do it. Everything's been on time so far."
The news is not quite as promising for Miguel Montero (broken finger) and Chad Tracy (microfracture knee surgery). Though neither of them has had a setback, their odds of being ready when the D-backs break camp are getting longer.
"The longer we get, the tougher it is, with Montero several days away from actually doing baseball stuff, and we're going to ease into that, too," Melvin said. "That one's probably a difficult guy to get ready for the season."
Tracy is in a similar situation, though he is gradually increasing his level of baseball activity. Sunday he participated in some defensive drills with the catchers, taking throws on the bag but keeping away from any kind of fielding or activity requiring lateral movement. He has taken batting practice throughout his rehabilitation process.
"We can do stationary drills with him," Melvin said. "We're maybe a few days away from getting out there and moving around side to side on a field. We're probably still a ways away from doing it in a game.
"The longer Trace isn't out there in game activity, the tougher it'll be for him," Melvin said of Tracy's prospect of making the Opening Day roster. "We do have different scenarios with him, whether it's a limited role, or a guy that's ready to go every day. I would doubt that [he'd be ready for an everyday role]. The farther we go along here, the more difficult it is to get him ready even in a limited role."
Owen Perkins is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.