I love the guy and after watching him consistently under throw receivers I started researching him in 2020 and this is what I came up with. First of all I will define the difference between "getting a running start" Stepping up in the pocket, and from the pocket.
Getting a running start is that play often to van Jefferson, where he roles out one direction then turns and gets a running start in the opposite direction and THROWS IT AS FAR AS HE CAN down the field. Both times Jefferson was on both Bombs and one traveled 51 yards in the air and the other traveled 53 yards in the air.
Stafford stepping up in the pocket is good for 40 to 44 yards (these are to Kupp) OBJ against the 49 res was open at 52 yards down the field and Stafford was only able to step into the pocket and throw it and the ball only traveled 47 yards
Throwing from the pocket, just using his release he can throw darts but after 15 yards he throws low and behind.
I will put his highlights on and you can see for yourself.