Input consistency is important but output consistency is largely a function of uncertainty. Clutch, destiny, and fate don't really exist; it's all a numbers game. DK is worse at contested catches than some and better than others, but talking about consistency in outputs is a fool's errand.
Consider that the inputs that DK can control are largely effort related. Things like his film study, physical fitness, gameday physicality, blocking effort, and technique execution such as route running or how he plays the football in the air. These are pretty consistent, even when it comes to aspects like his attitude that some here really dislike.
Contested catches are an output, and it's true that DK is not elite at them like a Dez Bryant or AJ Brown. However, nobody makes them all of them, and likelihoods of any sort are ultimately uncertain variables where randomness plays a role.
For example, we can quibble about DK's contested catch rate, but let's say it's lower than 60% and higher than 30%. The rate itself is going to vary depending on whether he's being shadowed by one of the best CBs in the NFL plus a safety (Broncos game), or whether he's going against a young less experienced CB (Patriots). Even if the rate was consistent, say 50% for example, it's still uncertain; like rolling a dice where a result of 4-6 is a catch. DK could go 2/8 in one game and 6/9 in the next game and that isn't necessarily controllable.