Pittsburgh Penguins side
Kovalev's trade helped the Penguins rebuild. They plummetted to the bottom of the standings and drafted players like Marc-Andre Fleury, Evgeni Malkin, and Sidney Crosby to help them turn it around. The jury's still out on their success in Pittsburgh, but the return for Kovalev helped them in that regard. Harry York never played with the Penguins and was never traded, meaning we just follow Kovalev.
Now, ironically, we follow Kovalev back to New York. Kovalev was traded alongside Dan LaCouture, Janne Laukkanen, and Michael Wilson for Rico Fata, Richard Lintner, Mikael Samuelsson, and Joel Bouchard, on top of cash considerations, but those don't matter here. Bouchard played seven games with the Penguins and had two stints with the Rangers but was never traded, ending that part of the tree.
Mikael Samuelsson played 22 games with the Penguins, scoring twice. Samuelsson was traded to the Florida Panthers at the 2003 NHL draft along with the 3rd overall pick that the Panthers used on Nathan Horton, a 2nd rounder that the Cats used on Stefan Meyer in exchange for a 2003 3rd rounder used on Daniel Carcillo, and the first-overall pick. That was used on Marc-Andre Fleury.
Fleury won three cups with the Penguins and was a staple of the greatness of the early 21st-century Penguins, who dominated the league. He's a member of the Minnesota Wild today, in his swansong season. In 13 years with the Penguins, Fleury recorded 536 stats, winning 375 for a 375-216-68 record. He had a .912 save percentage and a 2.58 goals against as a Penguin, dominating the league. Vegas picked him in the expansion draft, so that branch ends, but it's still a cool inclusion.
Daniel Carcillo never played for the Penguins; he was traded to the Phoenix Coyotes with a 3rd rounder for Georges Laraque. He wasn't traded, but he did play 88 games for the Penguins, scoring four times. He was a veteran for a couple of cup runs in the early 2010s, and the Penguins branch with Samuelsson fades here.
However, we can return to the initial trade for more names. Richard Lintner played 19 NHL games for the Penguins. He was only there for a cup of coffee and has a drastically shorter branch than Samuelsson. So, we move to Rico Fata, who also wasn't traded by the Penguins. He only played 100 NHL games with the Penguins, scoring 21 goals and 26 assists for 47 points, taking us to the end of this trade tree.
Kovalev's movement from New York to Pittsburgh is still being seen today. The player Pittsburgh lost to the Golden Knights when they entered the league in 2017 was acquired because of this trade two decades earlier. New York got Justin Falk in recent memory for most fans, and that stems from this trade. It's incredible to think of the ripples caused by one trade involving a New York Rangers Stanley Cup winner almost 30 years ago.