Kaman hasn't lived up to his preseason hype, but I'm not sure this is the right decision without knowing the rest of your team.
Drummond has been pretty good lately but his sub 50% FT will kill you. Kaman has actually put up very solid per minute numbers this year, he just isn't getting hte minutes I expected and I'm not sure why. He seems healthy, and even with Dirk out and Brand struggling he still wasn't getting much more than 20MPG.
Some might want to disagree, but I think Dirk coming back will have an overall positive effect on Kaman. I think he'll feel less pressure on offense, and should also get more open looks if Dirk goes out to the perimiter and stretches opposing defenses out.
I still think Drummond is the better option in certain situations, but not all. I have a team with Dwight Howard and 5 other sub 70% FT shooters. I added Drummond and am happy. I have another team who my worst FT shooter is 79%, but only 1 is a volume shooter, so I am not adding Drummond.