Hank Aaron was among the best three players in the game for over 20 years. He was an MVP and finished in the Top-10 in MVP voting an amazing 14 times! He was a 21 time All Star. He led the league multiple times in hits, runs, HRs, RBIs, BA, slugging, and OPS. He led the league in total bases 8 times. In short, he was great, both in his overall stats and when compared to his peers.
Blyleven made a grand total of 2 All Star teams in 22 years. He was pretty good for a long time, but comparing him to Hank Aaron is silly.