imo, Kristen was amazing when she first did THE APPLE TREE at Encores, and I was thrilled when the show transferred to Studio 54. However, something had happened in the intervening months, and when I saw it again at 54, all the subtlety was gone, and Kristen was working overtime to make the show work, On that basis alone, she did not deserve a Tony nomination for her Broadway performance.
On the other hand, she was brilliant all over again in ON THE 20TH CENTURY, and I was so dazzled that I went to see it again during its closing week, shortly after Kristen had her Menieres syndrome attack. Her problem was so acute that the show was stopped after her opening number, where she seemed a bit wobbly, and held up for ten minutes. We did not know about her physical ailment at that point (it was only reported later in the press), and when the show resumed the announcement was some lame comment about "technical difficulty" being corrected. Surprisingly, she performed the rest of the act, and even Act 2 but at barely half her usual energy. I only learned of her problem when I went home and online. The management should have stopped the performance totally, or perhaps brought in her understudy, but that didn't happen.
Don't get me wrong, I think she is a brilliant talent. But the variability of her performances, perhaps due to this ongoing illness, may be the cause to her being snubbed for another Tony.