If you noticed I listed ALL PRO selections, not Pro Bowl selections and there are WAY fewer guys selected to be All Pro than the Pro Bowl.
This depends on the source and the particular year. As for source, I have looked for a good All Pro internet source for a long time, and pro-football-reference.com now has a start on that. However, the pfr info is a mix of multiple sources and first and second team selections. This becomes misleading and renders their current info useless for the purpose you are citing here. For example, in 1991, pfr lists as All Pro: 5 RBs, 7 WRs, 7 LTs, 18 total OL, 13 DL, 14 LBs, 7 CBs, and 7 safeties. Don't those seem like high totals for those positions? To pick a single position for comparison, only 6 CBs made the Pro Bowl that season, and only 3 were named All NFL, which I consider to be the better source for this type of discriminator.All NFL info can be found
HERE.
For Bradshaw, pfr shows him as All Pro in 1975, 1978, and 1979. Here are the number of All Pro and Pro Bowl QBs shown at pfr for those seasons:
1975 - 4 All Pro QBs, 7 Pro Bowl QBs
1978 - 4 All Pro QBs, 4 Pro Bowl QBs
1979 - 5 All Pro QBs, 4 Pro Bowl QBs
Not really that much of a discriminator - 13 All Pro QBs to 15 Pro Bowl QBs.
A similar look at Aikman shows more of a disparity:
1993 - 3 All Pro QBs, 9 Pro Bowl QBs
1994 - 4 All Pro QBs, 7 Pro Bowl QBs
1995 - 5 All Pro QBs, 8 Pro Bowl QBs
Even so, 5 All Pro QBs in one season isn't really my idea of the very best. Once pfr gets its data expanded so we can look at, for example, AP first team All Pro, it will be much more helpful. (Doug has said it is on the list.)
Meanwhile, Aikman never made All NFL and Bradshaw made it once, sharing the honor with Jim Zorn in 1978. (Most seasons have only one QB on the All NFL team.)