I'm not arguing that at all. I've always said you need a balance. But yes, the NHL as a whole, forward groups on average are getting progressively smaller and faster. Whether a player is big, or small, you need to be able to skate decent enough. TB forwards weren't the biggest group, but they were faster than the Bruins forwards and willing to play physical despite their size.
No one is saying the Bruins are becoming soft smurfs. Who is suggesting that? But every day someone comes on this board and whines about the Bruins being soft and small.
You mention Pittsburgh, well it was noticeable during both their cups runs how often their forwards would lay-off on potential hits on D-men who just moved the puck, in favour of getting back faster and outnumbering opposing team attackers with that swarming man-to-man system they employed.
My Top 50 forwards? I could go Top 100, there are a lot of very good forwards in today's league, the gap between No.50 and No.100 wouldn't be that big. And why is 180 lbs your benchmark? Is a guy whose 5-10 185 big in your eyes, but if he lost 5 lbs now he's small? Besides player weights from website to website are all over the map, and player weights change throughout the season, so your benchmark is pointless.
Even some of the best forwards are big guys but aren't really physical. Connor McDavid is 6-1 195 according to some websites, and averages 0.25 hits a game. Auston Matthews is even bigger (6'3, 205) and records less hits than McDavid does.
Just using your benchmark of 180 lbs, going by TSN, the players the majority of all this softness talk is pointed towards is the young wingers. Well 3 out of 4 pass your benchmark of 185 lbs, all are 6 feet tall or above. So is size really the issue, or is it a willingness to play physical?