I trained wingers for a few seasons and didn't seem to do very well. Quit that and overhauled training to passing. Hope I didn't do it at the wrong time, cause training wingers is pretty easy.
For PM-heavy wingers, they provide a salary-free upgrade to midfield (and I think you'd have to work hard to overestimate the value of this), plus tactical flexibility. And there's very few of them, to the point that I doubt you'd get a TC on guys with WC+ PM.
Keep in mind that everything has gone through the roof in the current market, but if you were training uberwingers, then yeah, you might have gotten out of the market a little early (though I'd expect passing training to treat you pretty well too). I don't agree that it's easy to train wingers, though. You need a big initial outlay to do uberwingers right, if you can find trainees at all (I'm having a bitch of a time finding a replacement for the one I just sold).
I was just doing basic mono-skilled wingers, so in that sense they were easy to fill. Wingbacks were a little tricky w/ even less payoff. Overall, wingers were great tactically. Just buy some awesome IM's/forwards/cd and you can play them twice a week.
I'm in the market for a winger right now and the prices are high, and there aren't any American wingers of high quality on the list.
Multi-skilled players in general have prices soaring through the roof. Definitely a great time to sell before people decide to stop paying ridiculous prices for these players thanks to the new attendance formulas.