This blog post from a couple of weeks ago discussed whether or not BYU should expect to have to play an additional 15 to 20 plays per game on defense compared to 2012, due to the Cougars going with a very uptempo offensive scheme in 2013. The post’s conclusion was that based on historical data of other uptempo teams, that the number of additional defensive plays these teams faced was considerably less than Bronco’s estimate of 15 to 20 per game.
A question that arose while analyzing this topic was whether or not facing an uptempo team would affect the opponent’s own offensive tempo. Would their offensive pace increase because they get sucked into a track meet, or perhaps their tempo would slow down in an attempt to counterbalance the hyper-speed approach they were up against? The answer appears to be neither.
The bar chart shows a classic “bell curve” shape where the average time per play is almost exactly the same against uptempo teams as it is against the rest of their schedule. This is based on 270 games involving all teams between 2005 and 2012 which averaged over 80 plays per game for an entire season.
Another way of looking at it is the average seconds per play:
Uptempo teams: 20.97 secs/play
Opposition vs other teams: 25.08 secs/play
Opposition vs uptempo teams: 24.83 secs/play
So the average result of normal tempo teams playing against uptempo teams is that their tempo speeds up by 0.25 seconds per play, or a mere increase of 1%. Also worth noting is that normal tempo teams have a tempo that is 18.4% slower than their uptempo counterparts.
cougarstats 
I’m not certain either of the data sets address Bronco’s assertion. I don’t think Bronco is asserting that 1) ‘go hard, go fast’ is contagious or 2) that more offensive plays automatically equate to more defensive plays.
There are multiple reasons why a team might run more offensive plays on average. If you have a great defense which allows few first downs you would expect the offense to have a greater number of possessions and, therefore, have a higher than average number of plays per game. If the defense is the primary contributor to the number of offensive plays you wouldn’t expect the defense to play more than average. They might very well play less as they tend to quickly force opponents into turnovers or punt situations.
However, if the offense runs plays quickly rather than allowing the game clock to move significantly in between snaps then you would expect it could significantly increase the number of plays that the defense will have to play. It’d be interesting to see if there is a correlation between a team’s total number of defensive plays and their offense’s average time of possession per play.