In 2013 Shuck showed some signs of life, batting .293 in 478 plate appearances. He had a poor walk rate of just 5.6% though, among the worst in baseball, and he hit only 2 home runs, and so despite the nice batting average, his wRC+ was 97. That's close to league average, and if a player adds value in other ways, a wRC+ of 97 plays well, but Shuck (who's had success stealing bases in the minors) was just 8 for 12 in stolen-base attempts, and rated as below average defensively as a corner outfielder.
He's spent most of this year down on the farm, and has struggled in what playing time he's gotten with the Angels, batting just .167/.195/.250 in 88 plate appearances, giving him a wRC+ of just 22, fourth worst among 438 MLB players with 80+ PA this season.
He'll report directly to the big-league roster, but I'm not really sure what the need for another crummy left-handed hitter is, and I have a hard time seeing him make a real impact this month, or playing a significant role in 2015, given that there are at least half a dozen outfielders on the 40-man roster who interest me more.