The problem with assuming that De La Rosa is being kept from Rosario, whose defense often comes under scrutiny, is his two starts with Pacheco were almost identical to the one with Rosario. De La Rosa had dominant periods, but he ran into trouble and lasted just 4 1/3 innings each time.
"It's not," Weiss said when asked if this is a personal pairing. "You probably don't believe me. That wasn't the issue. I wanted Wilin to be in there against left-handed pitching we faced the first couple of nights. He swings the bat very well against left-handed.
"I need to get Jordan in there just because he hasn't been out there in a little while. Those were the bigger factors as to who was catching Jorge tonight. Wilin will catch Jorge plenty this year."
Facing left-handers on the first two nights of the series against the Padres, Rosario was 4-for-8 with a home run and three RBIs. In De La Rosa's last start, at San Francisco, Rosario was scratched before the game because of a left wrist strain from a previous game.
Thomas Harding is a reporter for MLB.com. Follow him on Twitter @harding_at_mlb. This story was not subject to the approval of Major League Baseball or its clubs.