I can guarantee you two things:
A) Jason Lane knew, as the play was unfolding, that the odds were that Monasterio was getting thrown out.
B) He also knew that there were two out, and Jahmai Jones, who had struck out all four trips this series, was the next hitter.
Given that knowledge, he went with the chance of a clean pickup, good throw, clean catch, another good throw, and a clean catch & tag might somewhere along the line get botched. Was it going to happen? probably not. But under the circumstances he made the right call IMO. I'm sure a lot of fans agree with you, just understand the stuff that goes into a decision like that.