SAN FRANCISCO — When the Giants called Bryce Eldridge up on Monday, Buster Posey and Tony Vitello talked about how days off would be coming for some of the team’s slumping veterans so that Eldridge and the red-hot Casey Schmitt could stay in the lineup.Luis Arraez got two straight, but not because of the logjam. Arraez hurt his left thumb on a swing on the last road trip and felt discomfort again in Monday’s game, one of his best all-around performances of the season. He sat Tuesday and Vitello said he “wasn’t feeling great,” and he was out of the lineup again Wednesday. The Giants are off Thursday and are hopeful that their second baseman will be available for Friday’s opener against the Pittsburgh Pirates. “You stare at that off day and rather than maybe get over the hump (now), you can tally up three days together,” Vitello said. “(That’s better) than kind of taking two steps forward, one step back.”Arraez is hitting .316 with a wRC+ of 109. He has made good on offseason promises to be better at second base and currently is tied for the MLB lead in Outs Above Average...