Just a word about the size of Walker vs the size of Davis.
Walker entered the league in 1996 as a 6'9" 220lb. PF.
Davis entered the league in 2007 as a 6'8" 290lb. PF.
Their body shapes and masses at the time of their entrance to the league couldn't be more different. An example of how different would be that if they both played football Antoine would have been considered an athletic, pass catching TE and Baby would be a prototypical offensive guard.
Walker was lean, and comparatively low body fat and was quick and had decent inside power to bang. Davis had comparatively a lot of body fat, was thick and muscular beneath the fat, and had an extensive size advantage in his lower body and trunk. He epitomized inside power and yet for a man his size is nimble and rather quick. Both have good hands.
If Walker was still in the 230lb range and in his best condition and if Baby loses 25 pounds of fat over the summer, Baby is still the much larger person and not necessarily fat. Walker is nowhere near 230. At 31 he would need to do considerable work to get back down to that weight. Baby at 22, with some self control and proper training will lose that weight, probably a ton easier than Walker could.
But either way if both men enter the league in their current condition, Big Baby would be a much more successful bench player because he has been playing and succeeding at playing at that weight for several years. Walker's game has been hampered by his physical conditioning and if he does work to improve his body will have a game who's quality will fall off the face of the planet.
So is Baby fat, yes. Is Walker fat, yes. But in proportion to their body shape, Walker is fatter and older and that is not a good mix. Both players could stand to do some weight training and cardio and shed some lbs.