Just because I have the info handy, here are the Norris records of Horton and Pronger:
Tim Horton
53-54: 4th
54-55: 6th
60-61: 6th
61-62: 5th
62-63: 3rd
63-64: 2nd
64-65: 4th
65-66: 9th
66-67: 4th
67-68: 3rd
68-69: 2nd
70-71: 12th
72-73: 9th
Chris Pronger
97-98: 3rd
98-99: 4th
99-00: 1st
01-02: 5th
03-04: 3rd
05-06: 7th
06-07: 3rd
07-08: 8th
09-10: 5th
And here is Earl Seibert's Norris equivalence record based on my method of tallying early All-Star votes:
All-Star voting records for defensemen (1930-31 to 1967-68)
Earl Seibert
31-32: 7th
32-33: 10th
33-34: 4th
34-35: 2nd
35-36: 4th
36-37: 3rd
37-38: 4th
38-39: 4th
39-40: 4th
40-41: 3rd
41-42: 1st
42-43: 2nd (partial war year)
43-44: 2nd (war year)
44-45: 7th
Just by eyeballing who left for the war, I'd estimate that Seibert's 1st Team nod in 1942-43 is probably a 2nd Team in a normal year, and his 1st Team nod in 1943-44 may or may not even be a 2nd Team! Remember finishing 1st or 2nd in voting = 1st Team, finishing 3rd or 4th in voting = 2nd Team.
Overall records:
Horton: 2, 2, 3, 3, 4, 4, 4, 5, 6, 6, 9, 9, 12
Pronger: 1, 3, 3, 3, 4, 5, 5, 7, 8
Seibert: 1, 2, 2', 2*, 3, 3, 4, 4, 4, 4, 4, 7, 7*, 10
' partial war year
* war year
Pronger clearly has the best season (weak Hart winner or not, neither Horton or Seibert was ever close to winning the Hart. Seibert barely beat a fairly weak field in 1941-42 for most All-Star votes; Horton never won the Norris). But Pronger also has significantly fewer seasons of high Norris finishes.