Seahawks have one of NFL's toughest 2018 schedules -- at least on paper

We already know a few things about the Seattle Seahawks' 2018 schedule even if all of the dates and times won't be announced until spring.

We know the teams Seattle will be playing, which include those from the AFC West and NFC North as part of the NFL's opponent rotation. We know that one of those games will be played in London against the Raiders in Week 6.

And via ESPN Stats & Information, we also have some semblance of where the Seahawks' schedule ranks in terms of difficulty -- at least on paper. Seattle's 2018 opponents had a combined winning percentage of .523 last season. That's tied with the Browns and Rams for the fifth-highest mark in the NFL. By that measure, Green Bay has the toughest 2018 schedule with an opponents' winning percentage of .539 followed by Detroit (.535), New Orleans (.535) and Tampa Bay (.531).

Here's the full list with every team's strength of schedule for 2018.

The Seahawks will play five games against 2017 playoff teams: the Rams (twice), Vikings, Chiefs and Panthers. Carolina is the only one among those four that didn't win its division, but it still won 11 games and only lost out on the NFC South title by virtue of a tiebreaker. The long travel to and from the Oct. 14 London game will present a challenge even if the schedule-makers do the Seahawks a favor and give them an away game east of the Mississippi (at Detroit, Chicago or Carolina) on the front end and a bye on the back end.

So that has the makings of tough schedule on paper. But to quote the great Kenny Mayne: "Games aren't played on paper; they're played inside TV sets." Really though, games are played on football fields from September through at least December, and along the way a team's prospects can change quite a bit from how they appeared in February or even after free agency and the draft.

The Seahawks' 2017 season offered a few reminders of that.

How many people penciled them in for wins over Jacksonville and Washington after those teams won three and eight games, respectively, in 2016? Both of them beat Seattle while the Seahawks earned road victories over the Giants and Cowboys, which initially looked like two of their tougher games after those teams combined for 24 wins the year before. The Rams improved from 4-12 to 11-5 in one of the more drastic and unexpected turnarounds the league has seen in years.

Entering last season, Seattle's opponents had a combined 2016 winning percentage of only .455, which was tied for 25th. But that jumped to .523 once the season was over and the games were played. The Seahawks went 9-7, marking their first season without double-digit victories and a playoff berth since 2011.

You get the point: assessing an NFL schedule six months and a half months out can be dangerous.

More than anything, the improvement of the rest of the NFC West -- Los Angeles and San Francisco in particular -- accounts for the increase in Seattle's strength of schedule from 2016 to 2017. The Rams (seven), 49ers (four) and Cardinals (one) combined for 12 more victories than they had the year before.

Here are the Seahawks' 2018 opponents along with their records from 2017:

Home: Packers (7-9), Vikings (13-3), Chiefs (10-6), Chargers (9-7), Cowboys (9-7), Rams (11-5), Cardinals (8-8), 49ers (6-10).

Away: Lions (9-7), Bears (5-11), Broncos (5-11), Raiders (6-10), Panthers (11-5), Rams (11-5), Cardinals (8-8), 49ers (6-10).