According to a report in The Times, Arsenal are hoping to sign Everton midfielder Marouane Fellaini after making a £22m bid, which is believed to activate the Belgian's release-clause. As Chelsea and Manchester United have been linked, an early bid like this seems like the easiest way to get Fellaini, as a straight out bidding war, for either transfer fee or wages, would end poorly for Arsenal. Arsene Wenger is an apparent admirer of Fellaini, and was reported to have been interested in August 2011, before ultimately choosing the more signable Mikel Arteta.
That Wenger is an admirer of Fellaini surprises me. We know Wenger has an affinity for physical midfielders, but while Fellaini ticks the boxes of being big, and able to shrug off opposing players, but his technical quality seems to be less than what one expects from an Arsenal midfielder. While he has an ok pass completion rate of 79.3% (and bear in mind he doesn't attempt many long balls or through balls, passes that have more risk and a lesser chance of being completed) he's slow to move the ball and has an inconsistent first touch. That seemingly would mean he couldn't play as a box to box midfielder; as Jack Wilshere and Aaron Ramsey showed last season, as did Abou Diaby, there needs to be technical quality and creativity from Arsenal's second midfielder if the attack is going to flourish. Even with Ramsey, the speed of transition from defence to attack needs to be improved; Fellaini's not the player to do that.
Fellaini could also play defensive midfielder, the position he was signed to play for Everton. He's not played it often for Everton, because their needs must elsewhere, but also because Fellaini has an Alex Song-esque habit of being caught out and committing lots of fouls, resulting in yellow cards. Mikel Arteta may have committed only 6 fewer fouls than Fellaini (the Premier League's top fouler) but the Spaniard got 3 fewer yellow cards; not being suspended is rather crucial if one is to be a defensive midfielder. Also, as Arteta often starts Arsenal attacks, Arsenal would suffer if Fellaini was deployed instead, again because of the quality of the passing. Furthermore, playing Fellaini as a defensive midfielder takes away his greatest strength: his late runs into the box that lead to goals.
Most of those runs, though, come from Fellaini playing as #10. The thing about that is Fellaini doesn't really work as a #10 for Arsenal; as I argued here, Arsenal need more creativity less season, not less. Fellaini would offer less. He's a big name who has lots of highlights, but those highlights mask his weaknesses, weaknesses that would mean he probably wouldn't be the best fit for Arsenal's midfield, the most important part of their team. Because of that, and because he'd be a good fit for Manchester United, I'd be extremely surprised if Fellaini turned up playing week in, week out at the Emirates next season.