Area where house sales have tanked

[Brendan L.]

I'm looking to buy multifamily and my local market is the Berkshires. Population decline, low house sales, some of the lowest house prices in MA. However, rents scale decently. Take a look at these graphs:

https://www.trulia.com/real_estate/Pittsfield-Mass...

What does it mean that the number of house sales have tanked? Just that I should plan to own my property for a long time and it will be on the market for a while when I'm ready to sell? Or are there other red flags that might affect me that low house sales might indicate? What other indicators should I look at to help me decide if I want to consider really digging into investment here?