Pretty simple actually... look at the players he's playing with. You're going to the boxscore and taking statistics that are based on numerous factors and applying them solely to an individual, which is why when people evaluate QBs these days, they don't do such a thing.
I get the love for QBR as an ESPN groupie, but seriously, nobody recognizes that as a stat. Its QB rating, which nobody liked or understood, converted to a number between 0 and 100... thats it. Every other sports site on the planet mocks ESPN on a daily basis for coming up with another meaningless statistic that nobody knows how to calculate. Its a made for TV stat.
What makes you think QBs these days are judged by on completion percentage or even TD/INT ratio? If I considered TD/INT ratio to be a heavily weighted stat, then I'd think Andrew Luck has been a mediocre QB for years, but anybody that actually watches games can tell differently. If I considered completion percentage to be a heavily weighted stat, than RGIII is one of the best QBs I've ever seen.
If I actually watched other QBs play, nobody would be impressed by most of anything QBs are doing these days. As I said earlier, there's 6-7 guys playing at a high level, and then there's everybody else in a group who are sometimes good, sometimes bad, and are largely dependent on players around them to even win a game at this point. Flacco falls in that group. If the personnel around them is better (Tyrod), then they win more games. If its not, like a Stafford, then they aren't winning many games.
Numbers lie all the time. They lie when they have no context, they lie when you mix a bunch of numbers together to form a different number that nobody understands (hello QBR), and they lie when flaws of other plays lead to a statistical change in an individual player.
Numbers Lie? Tyrod and the bills have been playing with injuries as well. Sammy Watkins has been hurt and so has Shady. Im not saying Tyrod is better than Flacco, but Tyrod is better than Flacco this year. I watch both of them play. I don't just watch the Ravens, I watch football. Joe has regressed. He throws a lot off his back foot for some reason, and throws a lot of floaters that Anquan use to make up for. He also throws the deep ball to short, which we have seen this year. The only thing that made up for that was Torrey's ability to draw the PI on a lot of those underthrown balls. Joe doesn't have that now.