In Robert Slimbach's italic Adobe Jenson Pro fonts, the swash glyph for the uppercase character 'O' extends below the baseline (see left word in the picture below). At least to my untrained eye, this looks a bit odd, and I'm not sure if I can get used to it (the non-swash glyph is shown on the right for comparison). I've noticed that the swash glyph for 'O' also slightly extends below the baseline in Slimbach's Brioso font (where it looks much more appropriate), but not in fonts like Arno and Minion.
I haven't found any information about how the swash glyph for 'O' is traditionally drawn or what the various traditions or variants are. Could someone here enlighten me? Do people agree that the 'O' in the word on the left below looks 'wrong'?