People just don't appreciate how bad Flacco has been. Especially when talking about deep ball, depth of targets, and accuracy.
According to PFF, over the last 3 years Flacco has had the 10th lowest average depth of target, even when teams are stacking the box. With less defenders deep, Flacco is still amongst ththe most hesitant to throw deep. Probably because he understands he has not been good at it in a long time.
Looking into that more specifically, in 2016 Flacco had the 5th lowest average intended air yards per pass at 7.7 his average completed air distance was 4th worst at 5.2 yards. But wait, there's so much more. In situations he threw in pursuit of a 1st down, he threw the ball 1.3 yards short of the 1st down on average. Only 3 QBs threw shorter of the sticks. Knowing this, it is unsurprising that Flacco also threw the 9th least amount of aggressive throws that year. He truly is captain checkdown.
*aggressive throws are described as throws into tight coverage, where there is a defender within 1 yard or less of the receiver at the time of completion or incompletion
That was 2016, let's look into 2017.
2017
Average intended air yards- 6.6 - 3rd worst
Average completed air yards- 4.4 - 2nd worst
Throws at the sticks- short by 2.2 yards - 4th worst
Aggressive throws- 13.3% - 4th lowest
https://fivethirtyeight.com/features...cks-all-wrong/
Now that sounds all well and good, but it's even more bad news for Flacco, who has the 22nd highest completion % in general over the last 3 years. So even with his low depth of target, his accuracy is lacking, complete with being the 29th best in the league for completion % last year.
For even more context about how truly bad he is at throwing deep, among 49 qualifying QBs with over 300 attempts the last 3 years, he is 44th in yards per passing attempt.