To clarify what I had in mind and get some of these thoughts out of my head and down somewhere, here's what I've been thinking.
Club team ratings:
ELO which would start last year or maybe the year before and include all leagues that are eligible for the Champions League and UEFA Cup. Going back several years it is very tough to get good data, particularly from smaller leagues. If that were available, then going back would be fine except for the extra time commitment. One could probably include lower-tier teams which would hopefully have lower rankings based on getting beaten by upper-tier teams in domestic competitions. That's one issue that would need to be resolved - counting cup wins over teams that are in very low divisions.
Eventually the same could and should be done with the North and South American teams. Because they have international competitions such as the Copa Libertadores the same should be possible. I don't think there are matches between European clubs and those from the Americas where both sides are motivated, so I don't think a combined Elo-type ranking would say anything.
Some new stats
Players: +/- type stuff (goals for and against when on the pitch), scoring stats adjusted for the situation (so a goal to go up 4-0 late counts less than a goal to go up 1-0 late), other things based on availability of video replay of matches and surely there are a couple things I'm forgetting here.
Teams: Goal stats in different game states (up 1, tied, maybe playing with ten men etc.), some kind of expected points
Regular stats, tables and information
The stuff you can see at sky sports or whatever your favorite sports news site.
Deeper content for bigger clubs
Because there are some teams where it is possible to watch all of their league matches, it's possible to go a lot deeper for them. I want to focus on objective stats like clearances (when someone on the opposing team has a touch that goes into the penalty area and the defender sends it out of the penalty area), assists (having a touch that goes to a teammate who then scores a goal), secondary assists (after the last touch the opposing team, other than the goalkeeper, gets at most x touches before a goal is scored) as well as fairly objective stats like tackles, pass steals and the like. Mainly I want to avoid things like chances and even shots which are fairly subjective.
The same could be done with big competitions for which all the matches are televised or available to view online. I'm honestly not sure if this includes the Champions League as I would have to see whether the UEFA pay-per-view allows you to view replays of all matches from the group stage onward. I suspect that this isn't the case. I don't think that it's possible to get every single premiership game either. It may be possible to get FA Cup matches from pretty far out on, but I suspect it's only the last 8 at best. So this would have to be the World Cup and European Championship finals only it seems.
I'm still working on a system to predict the outcome of matches based on data available before the match takes place. Every week, perhaps after placing the bets
, I would post this for whatever leagues the site will cover as well as league predictions done via simulations.
I would take a look at things like which league is the best overall, whether a 2-0 lead is somehow dangerous, whether or not scoring just before half time is extra important, whether a direct-passing approach is better, whether some teams are actually set up to be tournament teams or if it's just variance, and whether taking long shots is a good idea.
As far as I can tell there really isn't a site out there with this type of stuff for soccer. There are for baseball, basketball, American football and hockey, but I haven't seen something similar for soccer, at least for free. The reason I asked about interest here is that 2+2ers are going to be the type of people that would like this stuff. I'm not sure how much interest there is since soccer fans tend to be resistant to a lot of this type of stuff. Obviously taking all of this on at once would be extremely ambitious. With nobody's help, I would probably work on some of the articles, the prediction algorithm, and the new stats for a few of the bigger leagues while very slowly getting the Elo thing done. In addition to whatever new ideas people would have, having people help would likely allow more leagues and some of the deeper stuff as well as getting the Elo ratings, and really everything, done at a faster time.