I know what you are getting at but the main shaft fracturing isn't a detail problem, I would suggest it's more than a small detail.
If you bear in mind that the design of shaft has run for millions of flight hours in the 332L, L2 and 225 without problem (up until last year), then the concept must be OK. Some detail changed in the manufacturing process recently (different surface treatments etc) and that precipitated the problem for the Bond ditching. (Whether or not for this one, we don't yet know.). So I would say that since a small detail change caused the problem - albeit a pretty catastrophic problem - it is a small detail change to fix it.