Can't remember the source, but I have read somewhere that Walker was boozing around at the time and came into the fight underprepared. Apparently he just managing to hold out Tendler, who was finishing strong. Might well have lost to Tendler had it been scheduled as a 15 rounder.
That Tendler was finishing strong is what I've read too, but I've also heard Walker got the jump on him through the first half of the fight with some strong infighting and had what was called a "big lead" before Tendler got back into the fight later on and made a better show of it with the rally you allude to. Despite Tendler's late round rally, the decision certainly seemed to be the fair one (and some indicate that it was a clear one for Walker), as there was never any controversy surrounding the verdict rendered in it.
Yeah I've never heard that Tendler deserved it, was only suggesting that given the bout's trajectory, Walker may have been overwhelmed if it was scheduled for a longer distance. In any case, a fully prepared Walker handles Tendler, and definitely wins decisively, which is to take nothing away from Tendler, who was a strong as hell, legitimately great lightweight.
Tendler perhaps could have been a champion in any other era, its a shame he had to contend with the likes of Walker and Leonard.
First 6 rounds all Walker's, in the 7th Tendler started meeting him punch for punch, 8th and 9th were clearly Tendler's. 10th round even. That is, going by AP round by round description.