Gentry's temporary absence, brought on by a lower back strain suffered early in camp, paves the way for Sam Fuld to make the roster. Fuld's first opt-out date is Wednesday, but he's now essentially a lock for the Opening Day roster after impressing his new employers this spring, particularly with his defense in all three outfield positions.
The odd man out here is Michael Taylor, despite a breakthrough spring performance. Out of options, Taylor entered Sunday hitting .308 with five doubles and three home runs in 52 at-bats, making him prime trade bait for the A's.
"He is certainly playing his way to an elevated role," Melvin said of Taylor, "but this will probably go all the way down to the end with him."
With Cook unavailable on Opening Day, the A's are likely to carry lefty Joe Savery in a bullpen that's also expected to include Jim Johnson, Sean Doolittle, Luke Gregerson, Dan Otero, Evan Scribner and Fernando Abad.
Offseason acquisitions Josh Lindblom and Drew Pomeranz are technically still in the mix, but they're more likely to begin the season at Triple-A Sacramento to be stretched out and provide starting depth, which is even more significant for a club that is without injured pitchers Jarrod Parker and A.J. Griffin.
Right-hander Fernando Rodriguez, already pitching in Minor League games after undergoing Tommy John surgery last spring, will also start the season on the DL, as expected.
Jane Lee is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.