The Celtics have a lot of non-guaranteed contracts at the end of their roster, with Ron Harper Jr. being a lock to make the team next year. Harper Jr. proved himself worthy of a roster spot with his contributions last year, despite not making the most of his Game 7 spot. He will likely feel the best about his standing with the team among those with non-guaranteed deals. The Celtics have two draft picks (No. 27 and No. 40) to help fill the available roster spots. Boston can take back more money in a trade and also use their exceptions this offseason, something that wasn’t on the table for them last year. The team will be trying to upgrade in the draft or free agency as well. Amari Williams has plenty of two-way eligibility still, so it’s very possible the team tries to get him back on that deal if he can’t make the team out of training camp. Dalano Banton will have to earn a spot during training camp since he’s aged out of Summer League action at this point. The bottom of the Celtics roster right now is a surprisingly crowded area with some impressive potential shown from guys at all positions. The team only has one player under a two-way contract right now (John Tonje) after promoting Max Shulga and Amari Williams from their two-way slots in the second half of the season. Shulga’s spot is certainly vulnerable given he was a roster addition for salary purposes at the end of the year. The Celtics are watching the NBA Finals closely this week as a top rival in the Knicks look more than capable of pulling off an upset. How can Boston best position itself to take down New York next season? A lot of it comes down to roster composition so let’s answer a couple of intriguing questions on that front in this week’s mailbag.