Silly to argue about who should start
It can only help the Knicks for Azubuike to get healthy and play well.
It is unlikely that Azubuike will be 100% this year, but a solid contributor at 80-90% come playoff time will still be extremely useful.
Who starts is not about who is a better player. Azubuike and Fields are both good players with all around games.
Who starts will be about chemistry, about how the rest of the team plays, who fits better with the starters and who fits better with the second team. This is something you can only discover by playing them in different situations for a while.
If Azubuike only plays in April, there will not be enough time to figure this out this year; and consequently Walsh may not know enough to decide between re-signing him, trading him, or letting him walk over the summer. If he can contribute in February, then this is a totally different [and positive] development.
Whenever Azubuike is able to contribute serious minutes, it is Douglas and Walker whose minutes will be negatively affected, particularly Walker.
Fields and Felton will benefit from playing 25-32 minutes per game rather than 35-42 minutes. Also, Felton and Douglas will be able to get healthy, which we will need if we want to make it to the second round of the playoffs.