Cust was mired in a 12-for-71 (.169) funk from July 24 through Aug. 17, going homerless with no RBIs in 23 games over that span.
He's been streaking in the other direction ever since.
Cust, who entered Monday's game against the Royals leading the A's in homers (20) and walks (78), is batting .371 with four home runs, eight RBIs and nine walks in 11 games from Aug. 19-30, netting a .489 on-base percentage.
"He went through a little bit of a cold spell there," said Geren. "He still had a high on-base percentage, though. He was swinging at pitches he was supposed to swing at.
"Now he's got it again. You feel like he's going to give you a good at-bat every time. If you give in to him, he can hurt you. You need to throw him good pitches. If not, he'll walk."
Much of Cust's recent success can be attributed to a mechanical change. The left-handed hitter has gone back to his old toe tap with his right foot, helping to trigger his load and generate more power through his lower body.
Cust, who had slid as low as seventh in the order during his slump, has been back in the cleanup spot for the past five games through Monday's series opener.
"I don't get into where guys hit too much," Geren said. "I'm not afraid to move them around. You just go with the guys that are hot. Statistically speaking, if you hit up in the order, you're going to get more at-bats."
The way Cust has been going, the more at-bats, the better.
Adam Loberstein is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.