TOP is often a reflection of the type of offense a team uses. Teams that run the ball tend to have significantly higher TOPs than passing teams -- even though they have the same Number of Plays.
You do realize that the difference between 2.3 and 2.4 is a mere 4.3%? Are you suggesting that a 4% difference is meaningful?
Also, how does a team end up with TOP of 1.4, 1.6, etc.? If you line up and run the ball three times and punt, it should be around 2.0.