The mandarin tree does have leaves -- only that they're brown/yellow
and they are scarce.
The fruit is very orange, however as I said before, it's very small..
(about .5" in diameter), and has been that size since I've moved in
three weeks ago.

Abundant but small fruit is apparently the last gasp of a dying citrus
tree. Citrus remains fresh on the tree for quite a long while, even on a
dying tree.

Not necessarily true at all!! I have a very healthy, young mandarin tree.
It gets tonnes of fruit, but all small. I need to remove most, if not all
the fruit for a couple of years, till it's more mature.

Jen