SCOTTSDALE — Because Luis Arráez met with the media after his one-year contract with the Giants became official, he wasn’t initially on the back field when the other infielders went through drills for the first time. Until Arráez arrived, Casey Schmitt took the grounders at second base.Schmitt was the starter heading into the offseason, and given how many holes there were on the pitching side, it would have been very easy for the Giants to stick with that plan. The 26-year-old has shown flashes at the plate in recent years and slimmed down a bit this winter to be more agile at second base, but Buster Posey and the rest of the front office spent all winter chasing middle infielders.Brendan Donovan was a target early in the offseason, and the Giants also were connected to Nico Hoerner and CJ Abrams in recent weeks before signing Arráez. After the deal became official, Posey explained why he felt it was necessary to seek out a new second baseman.“Casey did make some big strides last year. (Christian) Koss, the same thing — he made some big strides,” Posey said. “Adding a guy like Arráez, I think, is an...