This won’t be Tyler Greene’s only shot to prove he’s a legitimate everyday major league shortstop. But it’ll likely be his best. Less than two weeks ago, Greene was an afterthought on the Astros’ 2013 roster. He was Jed Lowrie’s backup. Lowrie was expected to be the club’s veteran on-the-field leader, and at the time rivaled second baseman Jose Altuve as the premier everyday player. Then Lowrie was out of the picture, traded Feb. 4 to the Oakland Athletics in yet another of the Astros’ build-for-the-future package moves. Even on Monday, Greene was overshadowed. Expected to platoon at shortstop all season with switch-hitting, slick-fielding Marwin Gonzalez, Greene, 29, was a righty the organization was betting could turn 11 home runs and 30 RBIs in 305 combined at-bats with the St. Louis Cardinals and Astros last season into something stronger this year.