The Cavs can benefit from a number of things, of course. They need shot-blocking, low-post scoring, outside-shooting and a three who can stretch the floor.
Although they need these things, you're hard-pressed to assume all of those holes can be filled in one offseason when you considering where they were before this whole rebuilding process. It would be very interesting to see them go after a guy like David West to anchor the post (as Conrad JUST suggested on Twitter).
Past that, there are other free agents who may opt out of their deals that can give the Cavs what they really need. Between West, Andre Iguodala, Kyle Korver, Anthony Morrow, and the potential drafting of Nerlens Noel, the Cavs have a reasonable shot at filling their biggest holes while saving money.
West, at the end of his career, could come in on a one-year flyer (two-year if you want to flip a potential expiring deal to a team looking to save money). If that doesn't work out, you can invest in Iggy on a multi-year deal to shore up the small forward position that has had an obvious gape left by LeBron James leaving. Adding niche-type shooters like Korver and Morrow can be cheap, yet effective, enough to put a formidable team on the court to chase a playoff berth as Kyrie Irving, Tristan Thompson, and Dion Waiters all grow into their own as faces of the rebuilding effort.
Though Kyrie's spectacular scoring and offensive wizardry can leave our jaws wide open, he still needs help with the burden of scoring and as well as having his defensive weaknesses masked.
The Cavs issues won't be solved in the span of one offseason, but having almost $24 million in cap space this upcoming summer makes it a lot easier. They have the face of the franchise, a couple of sidekicks and an injured veteran who nearly made the All-Star team in Anderson Varejao; now the Cavs have the chance to add more to a core that can contend for a playoff spot next season.