I will preface this statement by saying that I am a big Moeen fan. However, he really hasn't looked comfortable at the Test level as of yet. I'd be really afraid of moving him up the order and having him face the new ball with extra pace and bounce (even on these docile pitches). Batting lower down the order, he has typically faced tired bowlers with an older ball, this has helped mask some of his technical problems. He is a decent player of spin and so this also makes him a better fit lower in the order, in my opinion. His strikerate (44.94) just further proves that he hasn't quite found his feet yet.
With the ball, I agree. I don't think he is a frontline spinner. He never has been, not even on the county circuit. His coming out party was last summer against India and Sri Lanka where he was a revelation. But since then, he has
publicly admitted
that he is no longer confident enough to bowl the doosra for fear of getting banned. This has limited his arsenal. In saying all of that, he has still picked up wickets at a decent clip. Since his debut, his bowling average (31.38) is lower than Nathan Lyon, for instance, and his strikerate (49) is third best among all spinners over the last year.
It should also be noted, though, that he hasn't been as effective against WI, NZ and AUS. He was injured during the World Cup and since returning he hasn't looked quite the same. He has struggled with his line and length and his numbers aren't nearly as impressive: 19 wickets at an average of 42.31 and strikerate of 64.6.
As an unabashed fan of leggies, I'd like to see what Rashid has to offer at the Test level. The pitch at Edgbaston this year has been receptive to spin so it is possible that both Rashid and Moeen play in tandem in the next Test. Rashid in for Bell, move Buttler to 6, Mo to 7 and Rashid at 8. I can't see England picking two spinners in an Ashes series at home, mind.