<p>LOS ANGELES -- John Gast became the fourth member of the Cardinals' pitching staff to land on the disabled list this month as the Cardinals moved him to the 15-day DL on Sunday, after Gast was diagnosed with a left shoulder strain.</p><p>The organization will have a better handle on the severity of the injury after Gast visits with team orthopedist Lyndon Gross on Tuesday. However, Gast's minimum two-week absence requires that Cardinals find another starter to plug into the rotation.</p><p>Gast described his left shoulder as "pretty sore" a day after he faced six batters in an abbreviated start against the Dodgers. The club has since learned that Gast had been dealing with shoulder soreness throughout this season, though he did not alert the Cardinals to any issues until manager Mike Matheny pressed him for an explanation as to why his velocity was down and his command off on Saturday.</p><p>In hindsight, that shoulder tightness may explain why it had been taking Gast longer than usual to get his arm loose while warming up in recent weeks.</p><p><a href="http://stlouis.cardinals.mlb.com/news/article.jsp?ymd=20130526&content_id=48656618&vkey=news_stl&c_id=stl">Keep reading...</a></p>