Salres reps often start as in-bound - working form their office. They call you, you call them, but they don't usually visit. Those that do well get promoted into different geographic areas. Those that do really well often get promoted to having an area and become outbound and can visit clients.
So don't take it as a bad sign - you've probably just had a run of good sales reps. Or bad ones I guess, and they left.
A lot of promotions happen around year end as well (31st of July). So expect lots of job changes around that time.