Last year, one of the major issues for the Knicks all season long was their perimeter defense.
Iman Shumpert is a great defender, but he can't do it all on his own. Adding Tim Hardaway Jr. to the mix certainly helps, although there is still room for two more defensive players on the wing.
As someone who can guard three positions, Tony Allen would be great, but realistically it's hard to see him leaving the Memphis Grizzlies, especially if the Knicks can only offer him the veteran's minimum.
With that said, the Knicks may have a shot at landing Matt Barnes with the minimum, as according to ESPN, he's already expressed an interest in joining the team.
Barnes is clearly worth more, but he took the minimum salary last season, and may be willing to do the same again for a chance to play for a contending team in New York.
If Barnes instead decides to cash in on his value, the Knicks' options are limited. They should be able to sign Marquis Daniels as a third-string shooting guard, and could bring back Ronnie Brewer if Barnes isn't an option.
Best Option: Matt Barnes
Realistic Alternatives: Marquis Daniels, Ronnie Brewer