Moustakas, who re-signed with the Brewers on a one-year, $10 million deal last month, has never played a game at second base in the majors or minors.
He has been playing the position in spring training, however.
"I'm really enjoying it at second. It's fun; it's new. And I feel comfortable, which is the most important thing. I'm getting a lot of work over there," Moustakas told reporters, according to the Journal Sentinel.
Counsell admitted that Moustakas won't have "high-end range" but said he is "very instinctual as a player."
Moustakas, 30, has primarily been a third baseman in the majors, but Travis Shaw is starting at third for the Brewers.
Moustakas hit .256 with eight home runs and 33 RBIs in 54 games with Milwaukee last season after the Brewers acquired him July 27 in a trade with the Kansas City Royals.