I am not sure why I am getting so few results, but of smaller rookie guards in their teens, the Basketball reference search engine spits out only 6 guys: http://bkref.com/tiny/FalHS
3.7 Win Shares by Stephon Marbury is BY FAR the best output of a rookie 19 year old guard under 6'3" tall. Dajuan Wagner and (I had forgotten him) Eric Money registered positive Win Shares as 19 year olds, but just barely.
I suppose I should expand the search to 20 year olds - maybe guys graduate high school closer to 19? So, we do that and............http://bkref.com/tiny/12wNS Yep, that is the ticket. Guys generally are 20 years old in their first NBA season. Tyus will not be 20 until May 10, so he will play the entire season at age 19.
The five best young small point guards 20 and under have been Chris Paul, Derrick Rose, Brandon Jennings, Stephon Marbury, and Gilbert Arenas. Three of the five have been all-NBA in their career.
For Tyus - assuming that he is not Chris Paul (interesting note - the lovers of Tyus always compare him to Chris Paul) -- what is a fair expectation? Maybe the 20th best season of all-time, so, 0.4 Win Shares? That is pretty awful for a team that is trying to win games. So as a Wolves fan I hope Tyus is top 10, but that would mean he would have a better rookie campaign than Russell Westbrook. Hardly a "reasonable expectation."
Best wishes to Tyus, but history teaches us that a 19 year old small PG contributing a fair level of wins has not been done since Stephon Marbury -- maybe it is time to make it a Timberwolves tradition?