I think Tadej needs some racing to get fully into his rythm (as opposed to Roglic). The evidence is UAE 2020 and 2021. Ok, he won this year but not in as convincing manner as he could have, had he been in his top form. The we have Tour de l'Ain and Cirterium du Dauphine where he was nowhere near Roglič. The beginning of his Vuelta 2019 campaign was also not very convicing.
Actually, there could be two reasons for that now that I think about it. Either he needs a substatntial warmup before he reaches his top form or it's just attrition from the racing that affects others much more than him. Though if the latter was true, then he woun't be winning so many 1 week stage races because they are too short for others to feel real attrition.