then it is because SlapPlayer does not push the smoker correctly in the direction it should to break the tongue, since according to the method i understand it does so in a random direction.
you should look for some method that pushes the smoker in the direction up or with more push force.
maybe some method of this plugin can help you, sorry for not being of great help but my understanding about vectors is poor :/
https://forums.alliedmods.net/showthread.php?p=2347689