Not much difference in the stats. Shields career ERA is 3.72 compared to Buehrle's 3.81. Shields WHIP is 1.22 compared to Buehrle 1.28. If anything Buehrle likely better pitcher considering Rogers Center. His HR9 with Toronto 0.9, and HR/FB 5%. When Shields was at Tampa HR9 was 1.1, his HR/FB was 9%. Which will jump at Rogers. Shields much better off at non-homerun ballpark. He's #3 starter at Rogers.
Shields history at Rogers Centre not good. He's had 10 career starts, a 4-3 record, 4.09 ERA. But 20 home runs allowed in 70 innings.