Comp% is such a flawed and poor statistic. Yards Per Attempt is SO MUCH better than comp%, because it adjusts for offense. Let's say you have a QB who throws 5 yard curls on every play and completes 80%, and another QB who throws 20 yard bombs on every play but only completes 40%. Which QB is better? Comparing Comp% in this instance is so totally useless (unless you expect a QB to be able to complete as many passes on 20 yard fly routes as on 5 yard curl routes), but you can compare the YPA, which AUTOMATICALLY ADJUSTS for Comp% and also factors in the depth of the throws.
I believe it was Bill James who determined that, among all simple statistics in football (simple statistics being defined as any of the single statistics the NFL officially tracks or any combination of two statistics the NFL tracks via addition, subtraction, multiplication, or division), no other statistic correlated better with winning than YPA and YPA Allowed (and yes, that includes comp%).
I really wish the NFL would do away with all this comp% talk in broadcasts and articles. It's emphasized far too much- especially in the Passer Rating formula, which double-counts it (once in the comp% item and once again in the YPA item).