I think what may have happened is that Zack gained a lot, not some, fat and a lot of muscle, glycogen, and water. 1 lb increase in LBM does not equal 1 lb increase in muscle mass. Everyone on both sides were getting their panties twisted over semantics.
Also, Rip's ppl are more concerned with getting big (70s big), while Lyle's ppl are more concerned with being ripped. Different approaches appeal to different folks. While the amount of fat gain may not look like much to Rip's ppl, it would look like a lot to Lyle's ppl.