The 22-year-old Skaggs -- 4-4 with a 4.34 ERA in 12 starts -- can be activated as early as June 21, which would have him missing two or three starts. And Scioscia doesn't anticipate this being a prolonged injury.
"We're doing this more as a precaution to make sure it gets behind him," Scioscia said. "Hamstrings, they have a life of their own. You never know. But we don't anticipate it being longer than [the extent of the DL stint]."
Skaggs said he didn't really feel like he had a hamstring injury during his start, but once he got off the plane later that night "it was super stiff," so he didn't even throw his between-starts bullpen session.
"I don't know the exact play where it happened," Skaggs said. "I think it was one of those things where it kind of progressively got worse during the game, but I didn't really feel it because I was so into the game. It's kind of like a freak thing, because I didn't even notice it until I got off the plane."
Skaggs called the injury a "minor setback" and expressed regret that he would missing Tuesday's start against the A's "because they definitely left a sour taste in my mouth the last game I pitched against them. Looking forward to pitching against them again, though."
Santiago was optioned to the Minor Leagues shortly after going 0-6 with a 5.19 ERA in his first seven starts with the Angels. The 26-year-old left-hander had a 6.43 ERA, a 2.14 WHIP and a 1.29 strikeouts-to-walks ratio in the three starts that spanned 14 innings during his time in the Pacific Coast League. Santiago last pitched Thursday, giving up six runs (four earned) on 11 hits in six innings, and will take the mound on his normal four days' rest.
"He's making progress with his command," Scioscia said of Santiago. "He feels much better about what he needs to do on the mound, so hopefully he'll bring it into the game tomorrow."
Alden Gonzalez is a reporter for MLB.com. Read his blog, Gonzo and "The Show", and follow him on Twitter @Alden_Gonzalez. This story was not subject to the approval of Major League Baseball or its clubs.