The amount of times a domain has dropped may have impact on the SEO effectiveness.  The less amount of domain drops you have the better.  The best is if you can get an old domain with zero drops.

Hover the mouse over the Domain Drops number to see the dates when the domain dropped in the past.

This data is inserted at the time a domain is added to the database. Only domains that have a minimum TF of greater than '1' and referring domains greater than '25' will have the Domain Drops data.  This is due to the cost of obtaining this data.