No. "He fell off" far less than Forsberg.
I don't know how you can possibly argue that.
Here's Fedorov's stats + awards after April 1996 (end of his 6th NHL season), when he was 26-and-half years old:
Stats
1996-2001 (five seasons):
Points = 47th
PPG = 36th
Plus/minus = 19th
2001-2007 (five seasons):
Points = 42nd
PPG = 59th
Plus/minus = 88th
"Awards"
Top 10 scoring finishes = 0
Top 10 PPG scoring = 0
All-Star = 5th in centers (2003)
Now, compare to Forsberg, also after six seasons and from the same age:
Stats
2001-2008 (five seasons):
Points = 53rd
PPG = 4th
(2nd among players with 3+ seasons)
Plus/minus = 6th
"Awards"
Top 10 scoring finishes = 2
(9th and 1st)
Top 10 PPG scoring = 2
(1st and 1st)
All-Star = 1st in centers (2003)
Hart = 1 (2003)
Art Ross =1 (2003)
There can be no doubt who aged better from ages 26 through the early-30s; I mean, it's not even close. The difference, obviously, is that Fedorov had better durability, fewer injuries, and played longer.
If cherry-picking had an award, your name would be on it.
I'm not clear why you think how each player performed away from their Cup-champ, strong teams is "cherry picking". I think it's important to look at in comparisons, especially since these two went to new teams at around the same age.
Forsberg, however, played a mere 117 games with Philly and Nashville. Nevertheless, in those 117 games he was equally as dominant as on Colorado:
130 PTS / 117 G =
1.11PPG
Plus/minus =
plus 28
Goal differential = 163 for, 63 against:
+2.59 ratio (that's incredible!)
Fedorov's first 147 games after leaving Detroit (two seasons' total with the Ducks & Blue Jackets):
109 PTS / 147 G =
0.74PPG
Plus/minus =
minus 7
Goal differential = 160 for, 151 against:
+1.06 (that's mediocre)
So, no, I'm not cherry-picking, I'm pointing out the obvious -- Forsberg was an equally dominant player removed from his original, very-strong team, while Fedorov was a decent 2nd-liner.
Of course, full marks to Fedorov for having a much longer and ultimately more productive career.