I've come back over to the keep Rozier camp. Early in discussions of Rozier's future, I argued vehemently for trading him. However, my reasoning is more of a hybrid of the two ideas. Hear me out:
Rozier becomes a restricted free agent the same summer as Irving and Horford, 2019. The Celtics are expected to take their first dip into the Luxury Tax, something they can no longer avoid. Fortuitous timing will and standard rookie contract structuring give the Celtics bird rights to Rozier exactly when they are not worried about paying too much. Despite possibly racking up a bigger bill, keeping Rozier on a new deal will help to maximize his value to the Celtics.
Retaining Rozier benefits the Celtics in the short term in two ways. First, they are only paying him three million dollars next season, an unheard of price for a sixth man. Second, he will still hold this bench together with the expected improvements the team has been harvesting. The steady improvements are a major reason why this move also works for the long haul.
Signing Rozier beyond the 2019 summer will offer the Celtics a chance to collect on their patience. Most of us agree Rozier could be a starter and a fringe all-star. We point to his steady growth as a good indicator he will continue to grow. I agree, but there will be a point he will be strangled by his limited role. Just like a plant stuck in an undersized pot, we know it will struggle to grow. The best solution to this problem is to get a bigger pot with more soil, essentially more room. The same applies to Rozier. This is where both sides come together, just farther down the road than we expect.
Trading Rozier in the summer of 2020 will be the best opportunity for the Celtics to maximize his value. We will get 2 more seasons of steady improvements, he will get paid, and another team will be willing to pay near top dollar for a 26-year-old Rozier.
The extra two seasons out of Rozier will do a few things. First, it will help Irving weather his chronic knee soreness. Provide the bench scoring the team desperately will need, keeping this team's champion ceiling high. Allow the Celtics to determine what direction they want to go in the future. By paying Rozier, the waiting will open up new doors that they wouldn't have if they traded him this summer.
As for his trade value two seasons from now, Rozier will have ironed out some kinks in his game: possibly improved playmaking, higher shooting percentages, and better pick and roll defense. Rounding out as a player who can take on point guard responsibilities, on either side of the ball, will make a team, desperate for a starting point guard, salivate. This is where the Celtics get their return on Rozier. Affordable in this case doesn't actually mean cheap.