Rest assured there are many factors considered before your WR catches the ball, to name a few:
QB energy and morale, Qb's throwing, vision, strength,
length of the pass, angle of the pass, amount of stress on the QB during the pass and how well he deals with that, angle the QB has to turn before making the pass, amount of distance traveled before the pass, whether the QB is moving or not during the pass and how well he does that,
coverage on the receiver, energy and morale of the WR, catching, speed, jumping, agility, vision, and possibly even strength of the WR,
ability of the coverage on the WR, their energy and morale, their vision, their agility and speed, their jumping,
everyone's SAs,
and beyond even football logic, there's a random number generator affecting probably every single variable listed above and many more I don't know or can't think of.
Tough to worry about all that at once...
What I do is try to have my catching around my QB's strength or higher, to me this negates their throwing strength. My speed and agility as a general rule are much higher than necessary to catch the ball considering it's harder to get separation than it is to catch
I like my vision to be within a good distance of my catching since the attributes seem to be related when considering catching ability, one being the physical attribute that lends talent to the other, a skill in playing football. More logical than not.
Confidence? After I do everything else maybe. Consistency is important, but if you have high catching and everything else you likely are consistent until you get screwed by a random variable or are outmatched. I can see low morale being a reason for say.. 7 drops in one game, because you got unlucky the first time, then got unlucky again without any time to prove yourself, and from there you forgot you had the ability to catch...
This makes me wonder: How silly would a team look with all 100s in confidence and every other ability suffering? Throwing interceptions and drops, both O and D lines getting utterly trashed, but always at the top of their low quality game.
Just a funny thought. Like Wimp Lo in Kung Pow... "How do you like my face to foot style?!"