I agree with the premise that 2nd round picks can definitely amount to something, but Sessions fell far in that draft and arguably had early 2nd round type talent--he was 6'3", was a pure point guard and really showed his passing skills (at least in his freshman year; I think his lack of assist in his junior year really, really hurt his stock). At least he showed real precocious passing talent at a young age, so although I was surprised he was a late contributor to the Bucks, I wasn't overly surprised that he was able to muster a 22-assist game. Sometimes it just takes the talent surrounding you to unleash the true passing ability.
Singletary on the other hand is a scorer through and through--no one will ever confuse him as a pass-first type point guard. He's not a shooting guard in a point guard's body because he actually does have some latent PG skills, but it's not to the point where it's a good or elite level in the NBA; probably just an average passer by PG standards. Unlike Sessions, who had the height/passing combination to really thrive in the NBA, Singletary's scoring abilities are commonplace--can be found in almost any undersized SG trying to make the league. He's less of a sure thing to break out because of that. That's why I keep emphasizing, he needs to show something different from what he did in college. Obviously I can't make any judgments until summer league, but hopefully he can develop a go-to asset that will help him long term.