The PG situation in this draft is quite strange.
There are 4 PGs in the top10: Dilingham, Sheppard, Castle and Topic. They all have at least one obvious major flaw like lack of size, being a poor defender, weak outside shoot... After these 4 PGs, there is Devin Carter, who is older, without a major flaw and who is obviously not as talented.
Spurs must decide, among the top4 PGs, which are the ones with flaws that can be fixed or mitigated by their qualities. At #8 there should have 1 or 2 of the top4 PGs left. If Spurs view them as too flawed, Devin Carter makes a lot of sense. Personally, I would take Devin Carter over Sheppard and Topic.