I could be wrong, but my recollection is that Gettelfinger, while giving an excellent performance, was notably taller than Ebersole. Davie (also excellent) was far more credible as a younger version of Edie. It could be that simple.
Perhaps! That goes along with the idea I mentioned about matching up better with Ebersole. Ebersole is 5'10" and Gettelfinger is 6'. Little Edie was 5' 9.5". I couldn't locate Davie's height. Although speaking for myself, absorbed in the story, the height difference did not make an impression on me when I saw it off Broadway.