I was stuck in Silver for my first 100 competitive wins, even though I had an average of 6-9 MVP's every match, and rarely ever did anything other than top-frag. ;~;
I was at silver 3 I believe (after being inactive) with around 40 competitive wins, then I came back and got MG1 in around 30 or less wins later (with somewhat around 70 total wins)
I was winning 3 and losing 1, always. Took me no more than a couple days.