This was the year of upper/mid level eddys (lows) that parked themselves in succession over the western Atlantic, near and over Hispanola.
These features had significant impact on the tract and strength of multiple tropical cyclones that in other years may have become significantly stronger and generated a more significant threat to the US mainland and Florida.
This was also a year of significantly drier air persisting along the subtropical zone across the whole basin.
It will be interesting to see what if any meteorological explanation may be offered to explain these features. Certainly from a lay perspective, these things were anomalies and relatively unpredictable in a long term sense. I have actively been engaged on this site since 1998 and I have never seen this pattern in those fifteen years.