Tony La Russa believes it's "premature" to question the integrity of baseball's replay system just two weeks into its existence.

John Farrell expressed frustration after two replays calls went against the Boston Red Sox in their weekend series against the New York Yankees.

"One thing I'd say to John -- and I'd love to talk to him because I have great respect for him -- is that, in fairness to the process, we need to keep working at it," said La Russa, who helped devise the new system for Major League Baseball. "I don't know what the period of time is, whether it's a month or six weeks or whatever it is, but we all have learned from what we've seen.

"But I think it's premature to say the process isn't going to work or he doesn't have confidence in it because, in my opinion, the process has been really remarkable in how well it's worked so far. I'm amazed, in fact, that we haven't had more hiccups."