The Miami Heat very nearly pulled off an incredible rally against the Boston Celtics in Game 7 of the Eastern Conference Finals to make it back to the NBA Finals. Instead, they came up just short, and have been working on finding their way back to the Finals this season. Unfortunately, the early results haven't been very encouraging for Miami.

The Heat aren't the only title contender to struggle early on, but their 5-7 start has exposed the numerous holes on their roster in the early going. Miami hasn't looked like the same team that has managed to piece together a championship roster in past seasons, and it's beginning to become a very big issue for them.

There's still a lot of time for Miami to figure things out this season, but if they intend on making that turnaround, they are going to need better performances out of some of their key players. Let's take a look at who three of those players are, and see why their early season struggles have been so detrimental to the Heat.

3. Gabe Vincent

Gabe Vincent emerged from out of nowhere last season to become a key piece of the Heat's playoff run. He was a guiding presence for the Heat when Kyle Lowry was forced to miss time, as he was a strong distributor of the ball and a knockdown three-point shooter. For that reason, it was safe to expect Vincent to take on a bigger role this season.

Vincent has been handed that role, but he hasn't exactly made the most of it. Vincent's per game numbers are basically the same as they were last season (8.9 PPG, 3 APG, 2.3 RPG) despite the fact he's playing more minutes per game, and his efficiency from both the field (38.1 percent) and behind the arc (30.2 percent) have been awful.

Vincent has been pretty much the opposite of what he was last season. Vincent was a steady option who could guide the bench unit to successful outings for the Heat. Now, he's been a sporadic shooter who hasn't taken the step forward he was expected to in a bigger role. Vincent needs to play better moving forward, because Miami doesn't really have any options to replace him at this point.

2. Duncan Robinson

Duncan Robinson has found himself back in the Heat's rotation due to necessity. With P.J. Tucker leaving in free agency, and no one coming in to replace him, Miami has a huge hole on their roster. Robinson has been part of the solution, but he is at the risk of playing himself off the court once again.

Robinson only is a playable option for the Heat when he's hitting shots, because he's a complete defensive liability. Robinson struggled mightily with his shot last season, and things have only gotten worse this season. Robinson is shooting just 36 percent from the field and 33.9 percent from threes, which simply isn't good enough considering he doesn't do much of anything on defense.

Robinson's role isn't huge for the Heat, but they are basically forced to play him on a nightly basis at this point. He's not hitting nearly enough shots to justify his role, though, and his defense is still subpar. If Robinson keeps on getting minutes while shooting at these horrible splits, the Heat will continue to labor through an ugly start to the season.

1. Kyle Lowry

Kyle Lowry's importance to the Heat is clear, but through 12 games, he hasn't looked capable of being the player they need him to be this season. Lowry has seen more minutes on the court than he did last season, yet he's managed to regress in just about every category possible. That's a very concerning sign if you are the Heat right now.

Lowry's per game numbers have all dropped (13.1 PPG, 5.6 APG, 4.3 RPG) and his shooting percentages are the lowest they have been in the past decade (40.2 FG%, 35.5 3P%). Lowry has been serviceable for the most part, but the Heat need more from him, and so far he hasn't been able to step up and produce like they need him to.

Lowry is relied upon to play solid defense, facilitate on offense, and hit his shots. So far, he's been doing that, but not at the rate Miami needs him to. With Vincent also struggling behind him, the Heat don't have many other options other than to continue to ride with Lowry and hope that he can figure things out. But Lowry is already 36 years old, and there's a chance that he could be regressing right in front of our eyes. If that's the case, Miami could be in some big trouble.