What about Fedorov's regular season effort?
It's not like his skills magically dropped but fall from 1994-1996 (basically three 100+ points seasons) is huge - he dropped down to 60-70 points range. Sure it has something to do with DPE, but then why his production rise in tougher part of the season?
Many players likely see their offense drop in the playoffs because they're on a team that is simply out-matched (like, say, if you're on the Mighty Ducks, and both of your 1990s playoff runs see you matched up against the team with Nicklas Lidstrom and a nine-series winning streak). Players on high-seeds don't have this same issue, hence Fedorov recording 16 points in 1995 in the first and second rounds (sub-.500 teams) and 8 points in the third and fourth rounds. I don't mean to take away from his talent, because you don't produce that well without it (and he had some big series against quality teams), but being on the best team of the era means that you get more favorable matchups for offensive numbers when compared to players on lesser teams. Fedorov never had to play against the Detroit Red Wings; Teemu Selanne did four times.
On the other hand, Selanne had to work really hard during regular seasons to bring Ducks to playoffs. It sounds like Selanne was terrible in playoffs what is exagerrated. His production (his main goal) was rather very good outside 2-3 playoff runs. Uncomparable to Fedorov, but I don't agree it's some kind of black mark on his resume.
When he was an elite scorer, he had excellent playoffs - especially as a goal scorer. Sure, he didn't break 20 points in the Ducks' cup run, but the Ducks played three top-five defensive teams and a fourth top-ten defensive team; it wasn't a run built for gaudy offensive numbers.
Team GA
Ducks' Opponents
2006: 1, 13, 15 (out of 30)
2007: 1, 4, 5, 10 (out of 30)
Red Wings' Opponents
1995: 1, 5, 11, 21 (out of 26)
1996: 8, 11, 21 (out of 26)
1997: 5, 8, 11, 13 (out of 26)
1998: 2, 10, 11, 19 (out of 26)
2002: 1, 5, 17, 19 (out of 30)
Given a fourth round in 2006 or some easier matchups in 2007, and Selanne was capable of hitting 20-point playoff runs like Fedorov. 19 goals in 27 playoff games in the seven seasons in which he was a top-10 league scorer suggest that Selanne could play in the Spring, but didn't get the chance that often. Like you said, it shouldn't be a strike against him.
Fedorov has the best season, but you can say that about
most comparisons to Fedorov. For whatever reason, he didn't play like that again... ever. Fedorov was top-10 in goals once (Selanne: six). Fedorov was top-10 in assists once (Selanne: five). Fedorov was top-10 in points twice (Selanne: seven).
Even with his defensive edge, he just wasn't the offensive player that Teemu Selanne was - despite being in the most advantageous environment: a team with two legit #1 centers to split the attention and one of either Nicklas Lidstrom or Paul Coffey. And it's not like it's impossible to record high offensive numbers with high-level defensive play; we saw him do it in 1994 and on
some nights through the rest of his career. Teemu Selanne has been top-three in goals as many times as Fedorov has been top-five in Selke voting, so ask which of those feats has the bigger net contribution.
Think about it this way: Fedorov broke 70 points once since the dead puck era began in 1996-97. Selanne hit that mark every time for the first five years of the DPE, and it was when he fell to 72 points that everyone knew something had gone horribly wrong with his health.