Grandal, after all, is a switch-hitter, which can force some uncomfortable managerial decisions across the way late in games in terms of choosing a reliever.
"His presence off the bench is real and the other team has to recognize it when they start to make some changes out of the bullpen," Black said.
"When you have switch-hitters, it's tough because you have to decide which side you want him from. It really swings to the team that has the switch-hitters that gives them a lot more comfort as far as making moves."
Grandal is the only switch-hitter on the bench and one of three switch-hitters -- in addition to shortstop Everth Cabrera and third baseman Chase Headley -- on the 25-man roster.
On Sunday, Rene Rivera got the start at catcher with Andrew Cashner on the mound. So with Grandal catching on Tuesday, chances are Nick Hundley will start in Wednesday's series finale against the Dodgers.
The Padres won't carry three catchers all season and might not for the entire month. But for now, this mix is working.
"That can help us," Black said.
At this point, the five-man bench consists of the two catchers who don't start, a fourth outfielder -- either Seth Smith or Chris Denorfia, generally -- and utility man Alexi Amarista.
Corey Brock is a reporter for MLB.com. Keep track of @FollowThePadres on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.