Here are the candidates each year that a releiver won the Cy Young Award in the past 30 years. It doesn't look like the "there were no legit starting pitchers as candidates" argument holds up.
W-L IP ERA WHIP SO SV
2003
1 Eric Gagne LAD 2-3 82 1.20 0.69 137 55
2 Jason Schmidt SFG 17-5 208 2.34 0.95 208
3 Mark Prior CHC 18-6 211 2.43 1.10 245
4 Russ Ortiz ATL 21-7 212 3.81 1.31 149
20 wins seems to be some sort of magic Cy Young number with voters... If Schmidt had 3 more wins in 03 I don't think there is any doubt he would have won. As for the others, I either wasn't alive or didn't really follow the debate at the time to really comment on.
Agreed. As I already said, in order for a closer to win a Cy Young, he needs a fantastic year while no starter distinguishes himself with a stellar season (i.e. 20+ wins and sub 3.00 ERA). What's actually better than looking at the seasons when closers won the Cy Young is looking at the seasons when they received votes but didn't win. 2005
1 Chris Carpenter STL 19 132 140 0.94 | 21-5 242 2.83 1.06 213
2 Dontrelle Willis FLA 11 112 140 0.80 | 22-10 236 2.63 1.13 170
3 Roger Clemens HOU 2 40 140 0.29 | 13-8 211 1.87 1.01 185
4 Roy Oswalt HOU 0 2 140 0.01 | 20-12 242 2.94 1.20 184
5 Chad Cordero WSN 0 1 140 0.01 | 2-4 74 1.82 0.97 61 47
5 Andy Pettitte HOU 0 1 140 0.01 | 17-9 222 2.39 1.03 171
1 Bartolo Colon LAA 17 118 140 0.84 | 21-8 223 3.48 1.16 157
2 Mariano Rivera NYY 8 68 140 0.49 | 7-4 78 1.38 0.87 80 43
3 Johan Santana MIN 3 51 140 0.36 | 16-7 232 2.87 0.97 238
4 Cliff Lee CLE 0 8 140 0.06 | 18-5 202 3.79 1.22 143
5 Mark Buehrle CHW 0 5 140 0.04 | 16-8 237 3.12 1.18 149
6 Jon Garland CHW 0 1 140 0.01 | 18-10 221 3.50 1.17 115
6 Kevin Millwood CLE 0 1 140 0.01 | 9-11 192 2.86 1.22 146
2004
1 Roger Clemens HOU 23 140 160 0.88 | 18-4 214 2.98 1.16 218
2 Randy Johnson ARI 8 97 160 0.61 | 16-14 246 2.60 0.90 290
3 Roy Oswalt HOU 1 19 160 0.12 | 20-10 237 3.49 1.24 206
4 Jason Schmidt SFG 0 13 160 0.08 | 18-7 225 3.20 1.08 251
5 Carlos Zambrano CHC 0 8 160 0.05 | 16-8 210 2.75 1.22 188
6 Carl Pavano FLA 0 6 160 0.04 | 18-8 222 3.00 1.17 139
7 Eric Gagne LAD 0 3 160 0.02 | 7-3 82 2.19 0.91 114 45
8 Brad Lidge HOU 0 1 160 0.01 | 6-5 95 1.90 0.92 157 29
8 Ben Sheets MIL 0 1 160 0.01 | 12-14 237 2.70 0.98 264
1 Johan Santana MIN 28 140 140 1.00 | 20-6 228 2.61 0.92 265
2 Curt Schilling BOS 0 82 140 0.59 | 21-6 227 3.26 1.06 203
3 Mariano Rivera NYY 0 27 140 0.19 | 4-2 79 1.94 1.08 66 53
4 Pedro Martinez BOS 0 1 140 0.01 | 16-9 217 3.90 1.17 227
4 Joe Nathan MIN 0 1 140 0.01 | 1-2 72 1.62 0.98 89 44
4 Francisco Rodrigu ANA 0 1 140 0.01 | 4-1 84 1.82 1.00 123 12
And so on and so on...
I mean look at Rivera in 2004, 53 saves and a 1.94 ERA. That's almost identical to Eck's Cy Young season. The difference is that there wasn't a starter during Eck's season who had a truly stellar season. There was in Rivera's. As a result, Eck won but Rivera finished a distant 3rd.