Summary
Wanamaker is a smart, reliable point guard, but just doesn't have the offensive ability to create many plays. He's not the player that will make something happen in an isolation situation, and won't carve up a defense in the pick-and-roll either. Wanamaker's shooting numbers were way down this year, but the sample size is small enough that it's probably better to evaluate him using his career averages. While his career 31% three point shooting is better than the 17% shooting he hit this past season, that number is still below average for a guard.

Wanamaker does tend to finish well at the rim, but those numbers are also down this year. I think Wanamaker can be an effective backup point guard at times, but players of his caliber are probably only worth the minimum or slightly above.
 
Cap Considerations
Wanamaker will be a restricted free agent with a $2.8 million cap hold and Qualifying offer, and Non-Bird Rights. The Hornets could also choose not to give him the QO, making him an unrestricted free agent. This is likely since his QO is probably above his market value.

Since they will only have his Non-Bird Rights, the most they could offer him using the Non-Bird Exception is a contract starting at $2.8 million, and that includes the ability to match an offer sheet that Wanamaker would get as a restricted free agent. The Hornets could also use space space or their MLE to re-sign Wanamaker if he demands more than $2.8 million.

Other teams will have multiple ways to sign Wanamaker as even teams without cap space could possibly use any of the Non-Taxpayer MLE, Taxpayer MLE, or possibly even the Room MLE or Bi-Annual Exception to sign him. It's also likely he could be had for the minimum, especially if he is an unrestricted free agent.