It's just cascading probability.
The Manning family has produced exceptional players for football in college and the NFL
Arch has shown promise already in college to have a good probability of being very successful in college, despite limited play.
If the Manning family is 4 for 4 for producing successful college QB's, and 3 for 3 in NFL caliber successful QB's, there's a higher probability of 4 for 4 instead of 3 for 4.
I personally think its a high probability that he makes it to the NFL as a starting QB. I also think its absolutely silly to tank every single year for the #1 pick until he declares for draft which may not even happen until 2028 draft.
I also think its a higher probability that Loomis and Dennis Allen continue to produce a failed NFL product on the field, Gayle passes, Loomis moves the team or sells it to someone who moves it, then it is for the Saints to end up drafting Arch Manning and leading the saints to another superbowl.
I would also be happy to eat crow over that last statement. With hot sauce please.