You sound like jon jones prior to ufc 151; it wasn't dillashaw's first fight ever. Even though barao and soto are different types of fighters, tj has been fighting long enough to already be prepared for someone with joe's skillset. It'd be like if you were studying for a calculus test, then your instructor decided to take it easy on you and just give you trigonometry questions. You may not have been preparing for it, but at that point, you should already have the knowledge to pass the test.
No one is claiming that tj was losing the fight (unlike the people claiming gagnon was beating barao), but he didn't exactly dominate him, and he didn't get the finish until the fifth, whereas renan was able to put mitch away in the 3rd.