There are issues with both Prescott and Bryant.
According to the PFF article, Dez has seen catchable balls on 155 of his 260 targets over the last three seasons. This year is by far the highest percentage of catchable passes he's had.
2015 55.9% 38 of 68
2016 58.4% 52 of 89
2017 63.1% 65 of 103
Even so, 63.1% is still a low number. A good rate of catchable passes would be the equivalent of a high QB completion percentage, allowing for a few drops, which makes anything above 70% good, and above 75% Top 10 in the league. The 77.2% catchable rate on TWill's targets ranks 6th in the NFL among the top 50 targeted wide receivers, although his drop rate ranks 29th.
Top 10 Catchable Rate
(Air Yards/Target)
1 Amendola NE 84.7% (7.8)
2 Tate Det 81.3% (6.6)
3 Ginn NO 81.1% (12.7)
4 Sanu Atl 79.2% (7.6)
5 Allen LAC 77.5% (9.3)
6 Williams Dal 77.2% (9.3)
7 Humphries TB 77.0% (6.2)
8 Kearse NYJ 76.1% (9.1)
9 Fitzgerald Ari 75.7% (8.5)
10 Hill KC 75.0% (12.0)
Most of those players get the majority of their targets from the slot position, which is why Air Yards per Target is listed. But only one WR (Ginn) averages deeper targets with a higher catchable rate than TWill. Dez's average target depth is 11.7 yards.
Catchable Passes
target 20+ yards (NFL average ≈ 40%)
Bryant 3 of 14
Butler 6 of 6
Williams 2 of 5
Beasley 0 of 1
target less than 20 yards
69.7% Bryant 62 of 89
80.7% Williams 42 of 52
70.5% Beasley 31 of 44
71.4% Butler 10 of 14
all targets
63.1% Bryant 65 of 103
77.2% Williams 44 of 57
68.9% Beasley 31 of 45
80.0% Butler 16 of 20
Of the 50 WR with the most catchable targets in 2017, Dez's drop rate ranks 46th.
Drops
46 Bryant Dal 65 catchable 7 drops 10.77%
47 Thomas Den 68 catchable 8 drops 11.76%
48 Lee Jac 59 catchable 8 drops 13.56%
49 Richardson Sea 43 catchable 6 drops 13.95%
50 Cooper Oak 52 catchable 10 drops 19.23%