John Kerry was appointed by Obama as well, and he is certainly way to the left of Hagel, on every issue - and was swiftly confirmed, 94-3.
Hagel made plenty of enemies in his own party, by going against the grain on numerous occasions, often in a manner many considered seriously inappropriate. Endorsing Democrats for Senate in 2010 and 2012 did nothing to re-endear him to former colleagues either.
Over/under on Hagel's tenure is one year.
"It's always reassuring to find you've made the right enemies." -- William J. Donovan