The Knicks have five players on the roster currently who can play as a center, but with a preference to put Kristaps Porzingis as the power forward, the Knicks have had to hand Marshall Plumlee minutes late in the season to help with the loss of Joakim Noah. Even though he does have a guaranteed contract for next year, it is preferable that Plumlee does not see any minutes as the third-choice center particularly in the first 20 games when Joakim Noah will be suspended. 

I've identified six potentially low-cost free agents the Knicks could look at to cover those minutes- each of whom offer something different to Willy Hernangomez and Kyle O'Quinn. Three of those players are bigger types and the other three are small-ball fours that could be used if Jeff Hornacek wanted to play Porzingis more as the five. 

1. PJ Tucker (unrestricted free agent)

The Raptors will be in an awkward position at the end of this season, with Kyle Lowry ($12 million player option), Serge Ibaka, Patrick Patterson and PJ Tucker all facing the free agency market. If things do not go well in the playoffs, Tucker could be squeezed out. The Knicks previously showed interest in Tucker this season to help the defense. He'd certainly be an upgrade on Carmelo Anthony and Mindaugas Kuzminskas and Tucker could guard players on the perimeter and allow Porzingis to stay around the paint. He may cost around the $8-12 million mark on a multi-year deal which wouldn't be an awful move for the Knicks, but he's probably going to be the most pricey player on this list. 

2. James Johnson (unrestricted free agent)

James Johnson has been excellent for Miami this year, averaging 12.3 points per game this season and his three-point shooting is up to a more reasonable 34% (career 28% from behind the arc). Johnson can defend multiple positions and he's also shown he has a knack for attacking the basket against slower players. The Heat may struggle to keep him as they are already on the books for $90 million at least next season, plus they have to consider Tyler Johnson's poison pill contract and whether they want to keep Dion Waiters around. It's tough to assess what Johnson could attract in free agency, but he might be around the same price as Tucker. 

3. Alan Williams (restricted free agent)

The 24-year old big man has been a revelation for the Suns in the past month and a half. He's averaged nearly 14 points and 14 rebounds in his past 15 games and at 280 pounds, he is difficult to stop on the boards. At 6'8, he's a little too short to guard centers, but he can help Porzingis on the defensive glass at the very least, and Williams has shown he is a decent finisher in the pick and roll. Williams has plenty of upside, but he may want a bigger role than what the Knicks can give him. 

4. Jonas Jerebko (unrestricted free agent)

The Celtics will need to create roster spots for Ante Zizic and Guerschon Yabusele, two of the draft and stash prospects who they drafted last year who have progressed quicker than imagined. The Celtics are also in a bit of a jam over whether they want to pay Isaiah Thomas, Avery Bradley, and Marcus Smart, so any extra salary shed is important. Jerebko hasn't had a terrific year, but he still provides a little floor spacing (34% from three this year) and importantly, he has shown he can switch onto point guards when defending the pick and roll. He's not a great defender, but he's got the lateral quickness to keep up enough. He also only plays 16.4 minutes per game, so finding a role shouldn't be an issue. 

5. Amir Johnson (unrestricted free agent)

Amir Johnson hasn't had a big role for the Celtics this year, but he's still been useful on the glass. His skill set overlaps with O'Quinn's, so he probably isn't the best fit, but he may be a more affordable option if he is keen to take something around the mid-level exception. He's durable, he's arguably a better (or at least more consistent) defender than O'Quinn and Hernangomez and he's a valuable locker room presence. 

6. Joffrey Lauvergne (restricted free agent)

After a poor start to the year at the Thunder, Lauvergne has shown better signs for the dreadful Bulls in limited minutes. The Bulls have been +1.8 in terms of his on/off numbers, and although he's a sub-par marksman, that doesn't stop him from putting up three a game, which at the very least provides some floor spacing. He's not particularly good at any one thing, but he's versatile enough on both sides of the floor to play as a center or as a power forward. His career percentages have been 60% at the five and 40% at the four, which could be handy as the Knicks for some reason continue to put out dual-centre line ups. The Bulls will probably be more interested in keeping Cristiano Felecio, so its likely Lauvergne goes elsewhere.