While it is a good university program and is nothing to sneeze at, it is definitely not an upper tier IM program. It is made more competitive by the sheer fact that it is in Boston but is not even in the top 3 programs in Boston proper and unlikely to be near the top 25 programs in the country.
I already stated it's not a top 20, but the fellowship match potential is stronger than the majority of "mid tiers" (look at the match lists). It trails right behind the top 25. And the "top 3" programs in Boston are Harvard x3, of course most programs lose to those. Plus DO's are not matching into the Harvards or most the top 25, thus this is a great accomplishment in that context.