Winger toward middle
A Winger who is given the order "Towards Middle" (WTM) is ideally an extra Inner Midfielder (IM)with a modest amount of wing skill.
Mostly PM and stamina are required. Passing and Defence are used as well, just like an extra IM. Basically, a WTM should be an IM that you would play normal since both his defence and passing comes into play somewhat. However, the wing skill of the WTM can come into play in two ways.
WTM and Winger Special Events
Wingers Towards Middle are still Wingers, therefore they can benefit from Winger SEs.
From the rules: Wingers with sufficient winger skill can create chances that will have to be finished off by another winger or a forward. If that other player is a head specialist or has sufficient scoring skill, he will score.
How much wing skill is "sufficient" is up for debate. However, WTMs with very modest wing have been known to generate WTMs. There is no clear evidence that high wing skill generates more Winger SEs.
WTM plus FTW/WB
If you are planning on playing a Forward Towards Wing (with high wing skill)in front of your WTM, and/or an Offensive or Normal Wingback with some wing skill behind the WTM, then some wing skill on the WTM can contribute to a modest wing attack without playing an Offensive Winger.