Adding additional slots in gear = diminishing effect?

[Rhode]

So, I got my Splatoon amiibos today in the mail and I snagged the gear from the challenges they give.

I added a slot to the body, and noticed that even though it has 3 slots, it is still considered a two star item. Does this mean the item is inferior, or is it on par with other 3 star items?

As far as I know, the star rank is only an indication of how many native slots the piece has, however I was told that it also determined some hidden stats like base defense, speed, and strength.

 

[AGES]

My guess is that its used to show people online how many abilities each piece of clothing initially had, so that if/when they order it from spyke they only receive as many abilities as the stars show. Sure, it would be unnecessary for the amiibos since you can't order them, but I don't think there would have been much of a point for Nintendo to change it for just that.

Never heard of hidden base stats before.