You're looking at time when you should be looking at amount of 3rds.
From 2005-2020 we drafted 12 3rd rounders.
Of those 12 the successful ones were Letang, Guentzel, Murray and Rust. That's a pretty admirable hit rate for 3rd rounders.
Sundqvist and Bortuzzo became NHL'er regulars too.
So far we have 7 3rds lined up for the next three years. There's gonna be more to come too. By the time Dubas is through we may match the quantity of 3rds from 2005-2020 in a span of 3-4 years.
The problem is, it doesn't really look so great if you break that up into smaller segments.
Break that down into 5 year blocks, and we get:
2005-2009: 5 third round picks, which yielded Letang and Bortuzzo as notable players
2010-2014: 4 third round picks,
all of which became NHL players: Rust, Sundqvist, Murray and Guentzel
2015-2020: 4 third round picks. Zero total NHL games out of them.
So, the actual success is from a long while ago, under different GMs, different Scouting Directors and different scouts.
That's a bit more concerning, and really, it doesn't look all that much better in the other rounds, either (though for once, the Pens seem to have actually done better in the second round than the third in that timeframe).
On the other hand, we've seen a more recent turnover of the scouts again, so maybe we can't really rely on any of that data to tell us a whole lot about the near future anyway