Why do you not think he is better? Hype? Potential draft status? None of those equate to winning college football games or who is better at leading their team right now.
If you really want to dissect further on who was more deserving of All-American honors in 2015 here's the comparison of the top 50 defenses they faced.
Rosen vs #18
15-of-30, 220 yds, 1 TD, 0 INT (QBR: 68.4)
Stockstill vs. #1
22-of-42, 174 yds, 0 TD, 1 INT (QBR: 48.4) FYI: better than six SEC QB's did against Bama that year
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Rosen vs #31
11-of-23, 106 yds, 1 TD, 3 INT's (QBR: 5.6
)
Stockstill vs #12
32-of-51, 286 yds, 1 TD, 0 INT (QBR: 39.7)
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Rosen vs. #41
19-of-37, 227 yds, 1 TD, 2 INTs (QBR: 55.4)
Stockstill vs. #15
29-of-42, 330 yds, 3 TDs, 0 INT (QBR: 63.9)
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Rosen vs. #43
22-of-42, 326 yds, 3 TDs 2 INTs (QBR: 45.6)
Stockstill vs. #42
21-of-34, 354 yds, 3 TDs, O INTs (QBR: 77.3)
Totals vs. Top 50 Defenses
Stockstill: 104-of-169 (62%) 1,144 yds, 7 TD's, 1 INT (avg D=17.5)
Rosen: 67-of-132 (51%) 879 yards, 6 TD's, 7 INTs (avg D=33.5)
But yeah Rosen deserved to be the All-American that year. Clearly the better QB.