To Tristan again last night; once again, miracles in the orchestra, and some on-stage problems are more obvious.
Brewer occasionally sharped in the first act in both performances, and I will have to concede Joshua Kosman's point that occasionally and unpredictably, a note would drop out or simply sound as if it wasn't properly embedded in the phrase. I'm not conceding anything else, however, and I think those problems were entirely in Act I. In acts II and III, she was magnificent. None of her singing lacked detail or nuance; the rage and sarcasm in Act I were palpable and there was plenty of passion in Act II. In act III, her shock and despair gave way to ultimate transcendence. She simply can't be called "undercast."
I'll also concede that Kristinn Sigmundsson slid upward into notes at the beginnings of some phrases, but his majestic dignity overcomes all.
Thomas Moser, sadly, disappoints through consistency. Everything is sung in a pleasant mezzo-mezzo-forte, without much color or word-pointing. Yes, he phrases musically, but it's not enough. He has to conserve his voice to survive, and act III simply needs about twice as much as he can give. The direction doesn't help. He stands around lecturing the audience, not raving, ranting, fevered, desperate.
The marvelous Jane Irwin is seriously underused, physically, especially in Act I. Give her more to do! Too much standing around!
I wish she were offstage for all of Brangaene's watch; for the first, long bit, she is above the stage in a tower, so there is at least SOME sense of distance. But when Brangaene is off-stage, the effect is magical; you hear her from Tristan and Isolde's perspective, distantly, over a wash of misty orchestral sound.