The 6'3" 249 lbs veteran enters his eighth year in the NFL in 2012, after having spent his first six years with the Tennessee Titans and last season with the Cincinnati Bengals (landed on injured reserve in the preseason with a neck/shoulder injury). He has been a productive receiving tight end during his career, with career numbers of 251 receptions, 2,383 yards, and 12 touchdowns.
According to ProFootballFocus.com, Scaife graded out negatively as a run-blocker in 2010, ranked 57th of 63 qualifying tight ends in that area. In 2009 however, his most productive season in which he recorded 58 total receptions, Scaife was ranked 23rd of 61 in run-blocking, in addition to being in the top third of receiving tight ends. While many of PFF's statistics are subjective, they can help us gain a better understanding about a player: Scaife is an above average receiving tight end / h-back, who isn't going to be a real force as a blocker.
Nonetheless, the quality that Scaife adds that someone such as rookie free agent tight end Nick Mellilo, just released, doesn't is experience as a veteran player of the league. While Scaife's signing could mean that either Rob Gronkowski or Daniel Fells are taking longer than expected to recover from surgery, I believe that Scaife's signing merely indicated the team's desire to have a veteran presence at the position through June and July, and possibly training camp while the team remains thin at the position.
Assuming Fells and Gronkowski do return to health before the start of training camp, I view Scaife as a longshot to make the final roster. His receiving skills aren't up to par with Aaron Hernandez or Rob Gronkowski, and he isn't at the same level as a blocker as Fells or Gronkowski. While a strong training camp could provide Scaife the ability to wrangle a roster spot from the likes of Daniel Fells, the only way I envision Scaife making the final roster is in the case of an unforeseen injury.