I'm as big a fan of Koufax and Gibson as anyone. I am not sure how their performances in a very different era detract in any way from what Bumgarner did in 2010 when he was 20, in 2012 and again this year. Bumgarner performed this year at the highest level, with playoffs lasting nearly 30 days. Gibson and Koufax didn't do that and neither did Lolich but all that proves is the situations are not completely comparable on the field, with travel, night games, the media pressure and the distractions. He cannot control the opposition. Before the playoffs, most posting on this board had everyone but the Giants winning. Even before the series, the speed, bullpen and hitting of the Royals was most of the discussion.
With all the scouting information available these days which was not in 1965, 68, 69, it is a very different game. At age 25, Bumgarner has done things in the post season which compare with the best. He can't do it against the 65 Twins or the 68 Cards, but he did do it against the 2014 Pirates, Cardinals, Nationals and Royals and he did it at a level Kershaw could not duplicate in the post-season. It isn't like this guy came out of nowhere and he is continuing to get better every season.
Infielddad, change "could not duplicate" to "did not duplicate" in the next to last sentence and I agree with everything you wrote.