2. Jonathan Isaac
The Magic already established themselves as a strong defensive team, while the coaching staff had to manage Isaac's playing time. He played 58 games, which is a huge accomplishment for Isaac but still far from a full season.
So, the question is, what will the Magic's defense look like with Isaac playing 60 or more games and averaging around 20 minutes? Scary is one answer that comes to mind right away. The Magic were already an imposing defense while playing two non-shot-blockers as their main bigs. Neither Wendell Carter Jr. nor Moritz Wagner are great rim protectors.
Playing Isaac more would add another element to the Magic's defense. His rim protection may also be the difference in some close games. All of this, plus the question of whether he can be available enough to have such an impact, make him perhaps the biggest X-factor on the Magic.
Luckily, Isaac finally got a chance to go into the offseason without a serious injury he needs to rehab. That may be just what he needs to put together his best season yet and reach the potential Magic fans see in him. If that is the case, the Magic should look even better than expected. Defense will be what wins them most of their games.