We can think about the potential of connectors and gappers in terms of the possible straight draws that you can flop:
87: JT, J9, T9, T6, 96, 95, 65, 64, 54
86: T9, T7, 97, 95, 75, 74, 54
85: 97, 96, 76, 64, 54
84: 76, 75, 65
As you can see, the more connected your holding, the more frequently the flop contains a straight draw. The more gapped your holding, the less frequently the flop contains a straight draw. Moreover, the more gapped your holding, the less likely your straight draw is to the nuts.
For reference, check out this video on Suited Connectors vs Suited Gappers by Guerilla Poker on YouTube.