I've read the responses, and generally agree. However, I would assert that it's entirely on you.
Let me explain:
Let's say you go two nights per week for about two hours. Generally, most people train this amount, unless of course, you're highly competitive.
Well, if that's it, and you do NOTHING else, than after one year, both you and a yellow belt following the same training regimen, would be rather close.
If however, you do randori twice per week at the above schedule, then on Mon/Wed/Fri, you run, lift heavy and do some body training and do grip fighting (even solo) and band pull uchi komi--hitting a few thousand per week, then of course you'd be head and shoulders above anyone else.
Some would say you're a "natural" not having a clue that you spend hours training off the mat.
In addition to the above regimen, you buy something like Mike Swain's Complete Judo DVD set, Inoue's DVDs and maybe Israel Hernandez's DVD and watch them religiously, you'll be better than most.
And of course, if you add in a couple days of BJJ, you'll be a god!