[Lingo] Pronounciation from kanji: 下手 （へた）

[steven smith <sjs@example.com>]

In general for words with compound kanji, the word usually
takes its pronunciation from the kanji's 音読み, right?
What is going on with 下手?

I show readings for 下：
カ・ゲ・した・しも・もと・さげる・さがる・くだ纔瘢韭絎竢蹙くだ纔瘢韭絎竢蹙く
だ纔瘢韭絎竢蹙-くだ纔瘢韭絎竢蹙くだ纔瘢韭絎竢蹙おろす・おりる

For 手：
シュ・ズ・て・て-・-て・た-

For 上：
ジョウ・ショウ・シャン・うえ・-うえ・うわ-・かみ・あげる・-
あげる・あがる・-あがる・あがり・-あがり・のぼる・のぼり・の
ぼせる・のぼす・よす

上手 = ジョウ・ズ, exactly as one would expect.  But 下手
（へた）doesn't follow the pattern at all.  I see alternate
pronunciations/meanings for 上手 that do behave as I expect
however. What's going on here?

Thanks
Steve S.