Three albums into their reunion (which is the same number the original trio made before disbanding in 1988), Dinosaur Jr. have settled into their role as indie-rock godfathers with all the respect and familiarity the title affords. But where 2007's Beyond and 2009's Farm sparked under the embers of playing together again, I Bet on Sky sags a bit, occasionally sounding like J. Mascis and Lou Barlow solo trips, just like the last time they made it to a third album.