When Dave McKay joined the Arizona Diamondbacks staff as the team’s first base and outfielders coach, three of his outfielders were fast, promising young defenders. Then, the Diamondbacks traded away Adam Eaton and got back Mark Trumbo in the same deal.

And McKay’s new job got a whole lot more difficult.

The 6-foot-4, 220-pound Trumbo was drafted as a pitcher and groomed into a first baseman, third baseman and designated hitter, playing about 25 percent of his major league career in the outfield.

After the trade, which would effectively pigeonhole Trumbo in the outfield without a reprieve at a defensively less-demanding position, the doubters made themselves heard.

McKay, though, is unfazed by Trumbo’s perceived inability on defense. And he actually looks forward to working with the 27-year-old slugger.

“I get excited about that, I really do,” McKay told Arizona Sports’ Hot Stove Show on Monday.

“I’ve heard that before — I’ve heard it about Matt Holliday, who turned out to be a very good outfielder for us in St. Louis.”

Along with Holliday, McKay went on to point to his previous work with Chicago Cubs outfielder Alfonso Soriano, a converted second baseman who once garnered gold glove consideration for his work in left field.

“If you have a player who’s willing to work at it, which Mark Trumbo is, there’s a lot of things you can do,” McKay told the show.

“I point it out, he goes to work. The player makes himself good.The guy has everything it takes to be a good outfielder.”

Over four seasons in the big leagues, and 922 innings in the outfield, Trumbo has accrued a -5.24 ultimate zone rating as an outfielder. He has six career outfield assists and four career fielding errors.

“I talked to (the Angels and they) said when (Trumbo) started playing first base, he was really, really rough,” McKay went on.

“And they turned him into a really good first baseman, because he was willing to get out there everyday.”

But McKay, who has more than 30 years of coaching experience, hedged his hopes of turning Trumbo into the next Gerardo Parra or A.J. Pollock.

“Make all the routine plays, and we’ll go from there,” he said.