Which is really the heart of the matter.

See, Hilda has been building for a few days already, and has a tight, compact windfield. It's nearly as small a Hurricane CARLOS earlier this year, which had to have been the smallest, midget Full-On-Hurricane I've ever seen.

Whereas Ignacio, with the more impressive satellite signature, is still "winding up", and it's extensive spiral bands have yet to 'consolidate'. And while the nascent 'eye' sure looks impressive too, it's also a sheared system and is having a tough time establishing that critical inner-core circulation sufficiently aligned in the vertical to really lay claim as a strong storm.

Also quite possible with Ignacio, that the pressure falls have yet to translate into a strengthening wind field, being as large as it is. I've seen some promissing looking storms essentially 'fall apart' because the circulation fails to consolidate before other detrimental factors (shear, SST's, etc.) preclude any further strengthening.

Bottom line: Small Storms with a Small Circulation can undergo faster and more radical changes in strength than can larger, sprawling systems. One need only mention Hurricane Charley for a classic case in point.