1. Yes, there is little overall truth to the "it's hard to beat a team three times" trope.
2. However, it depends on what teams you're talking about. SJU beat DePaul twice; it would not be hard for SJU to beat DePaul a third time (or a fourth or a fifth) because of the quality differential between the two teams. OTOH if you have two teams that are relatively evenly matched, it is more like the coin toss theory: each time you toss the coin there is a 50% chance it will be heads. If you look at them independently, it's 50% each time. But if you look at it as a string of events, the odds of it being heads three times in a row is low.
You can make a good argument that SHU is a better team based on better record vs common opponents and more "quality wins." But they aren't MUCH better, I would mostly throw out the results of the game at SHU, and it remains my opinion that SJU has better talent and depth when properly deployed.
Bottom line is I don't think the results of the prior matchup are all that important in this game: it's a standalone proposition, I think it's pretty much a coin toss, and I expect it to be a rock fight. To me Ledlum is a big key to this game - he's the only player on our roster who I think could play for Holloway based on physical and mental toughness. The rest of the roster is going to need to step up in that department if they want to win.