Nunez, a corner infielder who has also been clocking time in left field, has drawn a slew of attention lately, thanks to a bat that's connected for 32 home runs in Triple-A.
Playing time will be hard to come by for the 23-year-old Nunez, who will likely see most of his at-bats as the designated hitter. A's manager Bob Melvin said an additional position player could be on the way, along with more pitching.
"We're still kind of talking about it a little bit, depending on how much pitching we think we're going to need," Melvin said Sunday. "You always feel like you maybe have enough and then something transpires, and you don't want to get caught short, so we're talking about potentially a couple more pitching callups."
The A's have used 28 pitchers this season, second highest in A's history to the franchise record of 30, set in 2015. The use of 51 players in total matches the season sum from last year.
Top prospect Franklin Barreto, promoted when rosters expanded Friday, started Sunday's series finale in Seattle at second base, giving Jed Lowrie a day off. Melvin said Barreto could soon do the same for shortstop Marcus Semien.
Jane Lee has covered the A's for MLB.com since 2010.