I'm going to do some research, but it seems like when Iowa St. wins it is generally on a last second field goal or by a very small margin.
Iowa wins some close ones, but generally when the Hawks win they do so in dominating fashion.
Ask and you shall receive
Since 1984
Iowa - 21 wins, average score of 35-13 (biggest outlier, 1985, with a 57-3 victory)
Iowa State - 10 wins, average score of 23-16 (biggest outlier, 2005, with 23-3 victory)
Number of times Iowa wins a game by touchdown or less = 4/21
Number of times Iowa State wins a game by touchdown or less = 7/10
If we want to say since 2004 is recent history
Iowa - 6 wins, average score of 26-10
Iowa State - 5 wins, average score of 22-16
Number of times Iowa wins a game by touchdown or less = 2/6
Number of times Iowa State wins a game by touchdown or less = 4/5 (with wins of 2, 3, 3, 3, 20)