^^^You got it!
Over a distance of a straight 5000m, Rupp may indeed currently be able to run it in a shorter amount of time than Farah, and even Soi, (since Soi has not run anything recent that indicates he is currently in 12:52 shape, while Rupp has).
However, the fact that the race is being conducted on a track where they are running in circles (instead of in a straight line the whole race) adds tactical requirements to be successful. Even though Rupp may now be faster than Rupp or Farah over a 5000m distance, what Farah and Soi bring to the table is the ability to more quickly accelerate (change gears) when running at 5k pace and sprint. They can't hold that top-line sprint more than 50-80 meters. But it is enough to get positioning and use the curves to their advantage.
Longosiwa also has that faster spring speed than Rupp, and that is how he got around Rupp with 250m to go in the recent Paris 5000m. But Longosiwa then slowed down (remember, they can't hold that sprint for more than 50-80 meters) to regroup for the sprint at the end. (Indeed Rupp, had to slow down to get around, but he eventually overtook Longosiwa by the end of the race.) When Longosiwa slowed down, two other runners (Soi and Alamirew) were coming on the outside of Rupp and boxed him in. Tanui came up too, and Rupp had to slow down and regroup to get around. The timing of the box with Longosiwa's sprint around and slowdown maneuver was quite unfortunate, if not planned (yeah, planned, in the sense these guys have a lot of racing experience and seen it all, and this was a classic overtake move.)
Since Rupp does not have that flat-out short sprint, change-gears speed to go toe-to-toe tactically with these guys, particularly since he is heavily outnumbered, then he needs to set up the race to his strengths, and the only way to do that is to flat-out run it wire-to-wire, at 12:50 pace. These guys with the sprint speed, but not in 12:50 shape, will drop. If they don't, then Rupp will make them have to earn their scalps for that race, while he comes away with the 5000m American Record.
To get the 5000m AR, Rupp needs to run the race suited to Rupp's strength. Of course, Rupp needs to be 'on' that day, like he was 'on' when he ran that 10000m AR recently; he needs to be well-rested and focused, not jet-lagged, not running a championship 10000m the week before. And Salazar needs to understand that a 12:52 effort by Rupp will require an ALL-OUT, SUPREME EFFORT, which means NO WORKOUTS afterwards, at least for a few days, when Galen runs it. If Galen has in his mind that he has to run a workout after the race, it very well could, subconsciously, take away from his capability to lay out an ALL-OUT, SUPREME EFFORT during the race.
Rupp's best chances of running a 12:50 5000m are to get on the heels of those pacers and stick to them like white-on-rice.
So what if such a strategy gets him 4th? That's all he is getting now trying to play sit-and-kick with the likes of a Soi that has quick, gear-shifting ability. Rupp needs to just put it in overdrive from the gun, equally pacing a 12:50 time-trial for the AR. In doing so, he may indeed end up dropping Soi or Alimeru (sp) that just aren't yet in 12:50 shape.
Nike may have to provide some extra incentive-pay to the pacers to get it right. It's likely that once the band of east-Africans see Rupp's pacemaker-following strategy, Soi (or one of his compatriots) will try to jump out in front of the pacemakers, then slow the pace down. Alberto then may have a valid DQ case for impeding if that happens. Or better yet, the pacers just run over anybody that impedes them.
BTW, this is the SAME strategy Rupp can use TO BEAT MO FARAH OVER A 5000m as well! Are you awake Alberto?!?!!