I dont think Vlasic and Dowell are really comparable in terms of quality. If they said one has to go and one can stay id be amazed if anyone chose Dowell, could be wrong though?
Vlasic has been playing at a higher level, has more experience, and has seemingly performed well at CSKA. Dowell has done OK at Nottingham Forest as well, albeit not set the world alight. I would like to see him start really influencing matches at Champ level on a consistent basis before he could be considered for the match day squad with us.
Same age, same height, and you would expect one of them to kick on now, with Vlasic being the favourite.
By the way, we sometimes forget that Tom Davies is a year younger than the two above. I think fans are a little quick to give the boy stick, when it is a real achievement for him to have made 68 appearances already at such a young age. I think the lad will be a superb player for us, given the time and space to develop.