In my humble opinion, Chan Gailey played "not to lose" games, relying on his Defense to put him in a position to win games, whereas Paul Johnson plays to win, which is reflected in him often-times going for it on 4th Down rather than punting and playing more aggressively on Offense.
It may have been true that Chan managed to win a few "big" games, however, the style was typically very boring to watch for the most part, even with Calvin Johnson on the field because Chan didn't have an Offense in place that utilized his skills most effectively (or have a passing QB who could make things easier on Calvin, which would have made him even more effective).
Some current opponents of ours think Paul Johnson's Offense is "boring" because they don't understand how explosive it can really be by any of the various RB's, WR's or our QB. When run correctly, our "flexbone" option can pick up huge chunks of yards on any given play, even going the distance, or we can get short yardage needed for a first down so we can maintain control of the ball to control the clock for our patented "marches of death". Keeping the ball away from opposing offenses also gives our defense a chance to rest and prepare for whatever the opposing offense may be doing, and if we score, it puts more pressure on opposing offenses so they tend to press to score, knowing they'll have limited touches in a game, which leads to mistakes on their part, giving our defense better chances for turnovers and sacks.
Finally, the Head Coach of the Arizona Cardinals recently said that "being a spread QB at the college level requires "no leadership". I think that speaks volumes about our QB's who line up under center...