Manager Lloyd McClendon said coaches Trent Jewett and Mike Rojas have been working hard with Zunino, who has now thrown out three of nine attempted basestealers.
"I thought he threw the ball extremely well," McClendon said. "Trent and Mike have done a nice job making sure he's in real good position to throw and is moving toward his target. But the other part of that is the pitchers giving him a chance to throw guys out.
"When you're 1.5 or 1.6 [seconds] to the plate, you don't have much of an opportunity to throw anybody out. He's made some good throws this year and had no chance because we didn't hold the runners, so we're starting to do a better job of that as well."
"The kid can throw," said Texas manager Ron Washington. "I've read some stuff, but now I'm seeing it. He's got some pop in his bat and he can throw. Maybe we've got to stop running on him."
Greg Johns is a reporter for MLB.com. Follow him on Twitter @GregJohnsMLB as well as his Mariners Musings blog. This story was not subject to the approval of Major League Baseball or its clubs.