That's 30 successful picks in the first three rounds. Then there's 15 listed from the final four rounds of which possibly eight can be called mildly successful or better. Those numbers are right around the league average. The success rate of picks after round three are historically much lower than those from the earlier rounds.

Throwing more later round picks at the wall might provide another success or two, but it would also result in many times more misses. Using those picks, instead, to move up into the first three rounds would give the team a much higher chance of individual success. You can still find the "diamonds in the rough", like Granderson, via UDFA.

A perfect example of volume of picks versus quality of picks can be seen with the Vikings. Since 2010 the Vikings have had more than the normally allotted seven draft picks every single year by trading down and accumulating more picks.

2010 8
2011 10
2012 10
2013 9
2014 10
2015 10
2016 8
2017 11
2018 8
2019 12
2020 15
2021 11

That's 122 picks over twelve years. They have only managed 13 Pro Bowl players over that period. What they did end up with is a lengthy list of players that are currently out of the league. Only 42 of those 122 have started at least one game. They have managed only four years with over eight wins, four playoff visits and only two playoff wins (yes, we know those two wins well).