Vasquez is serving the second day of a two-game suspension for his part in a beanball incident with the Phillies that happened last weekend.
"It's hard, because I want to do my job today," Vasquez said. "It's hard when you're here and you see the team play and you can't help."
Vasquez's original suspension was for three games, but it was reduced to two after he appealed.
"I was surprised when I first saw the suspension," Vasquez said.
The D-backs cannot replace Vasquez in the bullpen, and are therefore a pitcher short until Monday.