For what it's worth, lets look at the respective resumes of Reed, Monk, and Watters.
Andre Reed:
7 consecutive Pro Bowl appearances (1988-1994)
Ranks 4th all time in receptions (951)
Ranks 6th all time in receiving yards (13,198)
Ranks 10th all time in receiving TD's (87)
Art Monk:
3 time Pro Bowler (1984-86)
Ranks 5th all time in receptions (940)
Ranks 9th all time in receiving yards (12,721)
Ranks 29th(t) all time in receiving TD's (68)
Ricky Watters:
Elected to 5 Pro Bowls (1992-96)
Ranks 15th all time in rushing yards (10,643)
Ranks 15th all time in rushing TD's (78)
Ranks 12th all time in total yards from scrimmage
I've also added one other component to the comparison: how each of these players performed in playoff games. I've taken their total stats from all of their playoff appearances and divided them into the number of playoff games they appeared in to represent a statistical average playoff game for each player. Here are the results:
Andre Reed:
4.47 receptions, 64.7 yds (avg. 14.5 yds)
0.47 TD's
Team: 10-9 in playoffs
Ricky Watters:
60.6 yards rushing (avg. 3.8 yds)
3.7 receptions for 41 yds (avg. 11.08 yds)
1.09 TD's
Team: 6-5 record in playoffs
Monk:
4.6 receptions, 70.8 yds (avg. 15.4 yds)
0.47 TD's
Team: 10-5 record in playoffs
For what it's worth, those are the numbers I came up with. You can argue there's more than just pure stats involved in electing players to the hall of fame, but looking at the on field production I'd have to say of the 3 players in question here, Andre has the most impressive production on the field, and if you're even considering Monk or Watters, Reed has to be in.
Though I'm a Bills fan, it's hard to see an objective argument that a WR elected to 7 consecutive Pro Bowls and ranking in the top 10 all time in all major statistical categories at his position, isn't a virtual lock for the Hall.
Of all the WR's who have EVER played in the NFL... only 3 have caught more passes than Andre!