I thought he had redshirted. I guess not.
Welch redshirted in 2010, played in 2011, and was hurt in 2012. I think he'd be eligible then?
Ah, a little digging and I found the rule.
Sixth year of eligibility is granted in a situation where a player has missed two seasons due to an injury.
Case Keenum Houston QB is a prime example. He redshirted in 2006 due to an injury, then went onto start in 2007, 2008, and 2009. During his fifth year, he tore his ACL in the third game of the season, which luckily coincides with the 30% rule. So, he was granted a sixth year.
Welch has only one year of eligibility remaining after he's done this season. Unless, he is to suffer a season ending injury at his new school in pre-season or before 30% of his teams 2014-15 schedule is completed.
Interesting note, Chase Hounshell would be eligible for a sixth year seeing as he's missed the last two consecutive seasons due to an shoulder injury.