In terms of different ratings in the NFL games for different positions (CB, SS, WR, TE, OL, etc), soccer games do the same. The FIFA series doesn't do this but I can only assume it's implied but in PES 14 if you put a 90 rated Center Back in the midfield or up top his rating drops into the 50's, conversely if a Striker/Winger put in defense.
Back to the topic at hand the WC like the Olympics gains fair weather fans during their time period and some stay following but most forget about 15 minutes after it ends. I did that for the '94 and '02 Cups, but after the '06 WC I told myself I'd like to know who these guys are so I started to follow the EPL and Utd. and have been hooked since.
It felt like listening to the radio your whole life and then someone giving you all the other music out there in the world. It opened my eyes and in my opinion to how flawed the US sports dichotomy is. The constant commercials breaks, the crappy teams being rewarded (top draft picks in NBA, NFL, MLB, NHL,). These things just started to rub me the wrong way. I pretty much stopped following the NFL outside of NY Giants and marquee matchup games. Tank in the Premier League, Serie A or Bundesliga and prepare for your favorite players to leave and to see your team play in the minors.
Uninterrupted flow, relegation/promotion, cups and tourneys up the wazoo. Those were the first things that made me fall in love with the sport. The entire season is the playoffs, you win and you get the domestic glory and the chance to be king of the continent, It made me happy when baseball considered making the NPB Series champions play the MLB World Series champions.
I believe soccer is just on the cusp of exploding in the US. This country is very spoiled and really only likes winners and if the USMNT can make it out of the round of 16 or even the semis even though they wouldn't win it can gain the national momentum and support it deserves and give the nation an optimistic chance to win in '18.
The next thing and it could be a HUGE gamble for soccer in the US is to play the season August thru May like most of the world and go up against the NFL, MLB playoffs, and most of the NBA/NFL season/postseason and maybe some of those who are tired of watching commercials all the time or are looking for something to watch between the next game have a change of heart.