^ In most years, host federations are limited in how much they can water down the field to help their own skaters. The year after the Olympics typically features a lot of retirements from the top ranks, but under the rules each Grand Prix event must have one of the top three from the previous worlds and one of 4th through 6th.
Plus, skaters meeting certain qualifications are guaranteed two GP events, so host federations often have no choice but to invite a strong field.
Yes, that is true, and the top 3 seeds may get to choose where they will skate. But hosts can pick seed #6 instead of #4, and of 7-12 at Worlds, 10-12 rather than 7-9. Hosts are also aware of which skaters start off slowly in the early season.
MEN:
Skate Canada picked #6 RIPPON as their second seed rather than #4 Abbott (who won SC last year) or #5 Brezina. From Worlds 7-12, they picked #8 VAN DER PERREN, who doesn't usually skate well in the early season, and #12 FERNANDEZ.
The others:
ODA - DNQ for the FS at Worlds. Was #4 WR (World Ranking), #6 SB (Seasons Best list)
PREAUBERT - Did not compete at Worlds. #8 WR, #24 SB
GACHINSKY - #3 JW. #21 WR, #33 SB
NANRI - Did not compete in an ISU Championship. #34 WR, #60 SB
HOCHSTEIN - #5 JW. #33 WR, #38 SB
BERNTSSON - #15 Euros. #36 WR, #43 SB
BACCHINI - #16 Euros. #54 WR, #45 SB
Oda was picked because he trains in Canada and is popular with Canadian fans. On paper (based on WR and SB) Gachinsky and Preaubert were unlikely to give Reynolds much competition; Nanri, Berntsson, Bacchini and Hochstein were likely selected to help Jeremy Ten place above the bottom 4.
That is not to say that Canada is the only host that plays this game.
Except for #4 seed BREZINA (who reportedly has an injury) and Worlds 7-12, the TEB men's field is also on the weak side:
Worlds 7-12: #11 REYNOLDS, #22 WR, #20 SB; #8 KOZUKA, #13 WR, #12 SB
VORONOV - #16 Worlds, #14 Olympics, #16 WR, #15 SB
MROZ - #4 4CC, #23 WR, #23 SB; 7th and 8th in 09-10 GP
SONG - #1 JGPF, #2 JW, #17 WR, #29 SB
KOVALEVSKY - #16 Worlds, #43 WR, #41 SB
LIEBERS - no ISU Champ (injured much of last year), #50 WR, #54 SB
KELEMEN - #29 Olympics, #138 WR, #73 SB