It was Desmond's third go-ahead home run in the seventh inning or later this season.
"I just tell myself when I get up there for every at-bat, 'You're prepared,'" he said. "If you prepared for the situation, prepared for the at-bat, then the rest will take care of itself."
His other two go-ahead home runs came on May 15 against the Blue Jays and May 17 against the A's. Both of those came when the Rangers were trailing.
"This guy's locked in, in those situations. He's been there before," Banister said. "This is not new to him. He was an exceptional player over in Washington."
Desmond didn't sign with the Rangers until Feb. 29, after Spring Training had already begun. He scuffled out of the gates and was batting just .109 with one RBI on April 18.
Since then, he's batting .365 with eight homers, 36 RBIs and 36 runs scored.
"He's got a lot to prove, really in his mind, which makes him a dangerous player," Banister said "We're lucky to have him. He's come up with some huge home runs, big hits, up and down the game. There have been some special ones late in the ballgame."
Desmond has hit safely in 20 of his last 22 home games and recorded his team-high 24th multi-hit game of the year with his 2-for-4 effort.
Mound visit pays off
Desmond's home run in the eighth set the stage for closer Sam Dyson in the ninth. But things didn't go exactly according to plan.
Colby Rasmus led off the inning with a double and scored two batters later on a single to right field by pinch-hitter Luis Valbuena. Gomez, who had walked, moved to third on the single.
With runners on first and third, and one out, Banister brought his entire infield to the mound to talk things over.
"Talking about handling the baseball, settle the situation down a little bit," Banister said. "Wanted to make sure where we were throwing the ball if they decide to run. Just where we were at. Wanted to make sure we were clear on what we were going to do."