2009-2012 Abby played center on and off. He was a pretty damn good faceoff guy (around 53%). Much better than Sheahan is.
Filpula became Zetterberg's linemate on second line sometime between 2010-2012, but primarily in the 2011/12 seasons.
I don't think Abby would be a good top 6 centerman. Being is top 6 centerman is nothing like being a bottom 6 centerman.
My first choice for centering 3rd line would be Darren Helm followed by Abby. But neither will happen.
Ideally next season I'd like to see Larkin/AA get some 1st and 2nd line centering duties. I think Zetterberg is much more useful on the Wing if he's to stay top 6. And I think Abby would be a good winger up there as well.
If Z stays first line center then hopefully Larkin gets 2C and AA gets 3C (he could share 3C duties with Sheahan).