From the article:
"The 19,800 who left the Mass Dems represent about 1.3 percent of the 1.49 million enrolled in the party. And though the MassGOP gained several thousand voters, it actually lost more in the same time frame, when 5,911 quit the party to be unenrolled."
So, it essentially means that most of a very small percentage of GOP/Dem voters who decided to bolt their respective parties chose to become Independents. I did the same thing myself 15 years ago (bailed from the GOP to become an Independent) and have never looked back. I find it liberating to not be attached at the hip to either party. Blind allegiance to party just encourages the bastards.
I think this spells far more trouble for the GOP than it does for the Dems. If a significant percentage of those who bailed from their party vote for Trump in the primary, it increases the likelihood of the GOP experiencing a nasty break-up.