If the Cs shot the 3 point shot as well as they did last year, they would have the 4th best point differential in the NBA. A change in personnel (Fournier and Kemba most notably) hurt them in that regard, but other players have fallen off considerably. Most notably, JT is shooting 33.7% vs. 37.3% from beyond the arc, which alone translates into 1.6 ppg. He alone would move the Cs net scoring margin into the 7th best in the NBA regardless of the loss of good shooters if he were shooting 3s as well as last year (and JT's always been a good shooter beyond the arc). His consistency has been way off, too, and he was listed recently as one of the ten least consistent players by ESPN stats guru Kevin Pelton. Of NBA stars, only he and Steph Curry were in that category.
The other obvious factor is how badly the Cs have played in close games. The Cs are tied for 16th in W/L% vs. their net margin being 12th. Usually an indicator of winning close games. Last I knew, the Cs were 2nd worst in games decided by 5 points, and according to the expanded standings at ESPN, they're tied for 25th in W/L% in 3 point games and have the 2nd most losses (6) to Indy's 10. To me, that's maturity, leadership, and coaching, none of which are strong points currently.
IOW, I don't think health alone would transform us into contender status though we definitely would be better.