Costa, Sterling, Rooney and Stones face uncertain Premier League season

This Premier League season promises to be one of the most competitive ever, but there are some players from whom nobody really knows what to expect. Here are 10 of the most intriguing names heading into 2016-17.

10. Adnan Januzaj

Of the group of young players told to find new clubs by Jose Mourinho, Timothy Fosu-Mensah might be the most bafflingly cast aside, given his fine form at the end of last season, but Adnan Januzaj is the most intriguing. This is a player of obvious talent who has never quite delivered on his potential, either at Manchester United or on loan with Borussia Dortmund last season. When he broke through under David Moyes, he looked like the real deal, but was that because everything else was so awful that he seemed like a boy genius by comparison? Wherever he ends up, he'll be fascinating to watch.

9. Diego Costa, Chelsea

To call Diego Costa a Jekyll and Hyde footballer doesn't really do his mood swings justice. He can be devastatingly good, completely anonymous, wind up an opponent, complain outraged to the referee -- or all of the above, sometimes in the space of a few minutes. In his first season at Chelsea, he was everything onlookers expected him to be: aggressive, aggravating and a source of goals -- 20 of them in the league, in fact. But during his last campaign, he looked unfit and sluggish, and he managed just over half his previous goals total, in more games. So, which version will turn up this season? Will he respond to Antonio Conte's boot-camp-style physical training or push against it? It'll be fascinating to see how that relationship pans out.

8. Andros Townsend, Crystal Palace

There was a convincing case that Andros Townsend should have been in England's Euro 2016 squad, simply because he offered something different than everyone else in Roy Hodgson's 23. Those who championed his cause did so on the back of a well-timed run of form for Newcastle at the end of last season, but that was relatively brief. Now that he's at Crystal Palace, he has a chance to secure a key role for club and country in the long term. Rather curiously, at 25 and about to appear for his 12th club (nine of which he played for on loan), this season will be a first in one regard for Townsend: He'll be a first-choice player for a whole season, and thus finally has the opportunity to establish a little consistency.

7. Viktor Fischer, Middlesbrough

Ajax remains a fine breeding ground for young talent, and it looked like they had another star on their hands when Viktor Fischer scored twice on his debut, aged just 17. Things continued to look promising for the young Dane for a while, but a hamstring injury led to his missing 14 months, and when he returned, his career stalled. This is a punt for Middlesbrough, although at £3.8 million, he is a relatively low-cost forward upon whom they will not be relying. They have other players in all of the positions Fischer can play, and if it doesn't work out, it won't be particularly damaging. But if it does, and he realises his early potential, they will have a bargain.

6. Pierre-Emile Hojbjerg, Southampton

Like an embarrassing parent, players must occasionally wish that their managers would keep their mouths shut when gushing about them. So when Pep Guardiola compared Pierre-Emile Hojbjerg to Sergio Busquets early in his career at Bayern Munich, the young Dane might have cringed. Needless to say, it didn't quite work out like that, and after a disappointing loan spell at Schalke last season, the time came to cut ties with Bayern, hence his move to Southampton. The Saints' recruitment policy is so good that you'd hesitate before doubting this signing, but they have gambled on his early promise being realised by new manager Claude Puel.

5. Sofiane Feghouli, West Ham

One of the benefits of the sheer amount of money swirling around the Premier League is that free transfers are absolutely free of risk, with the wages paid to such players basically chicken feed to these clubs and about as significant as an accounting error on their books. That's why it was something of a no-brainer for West Ham to sign Sofiane Feghouli after his contract expired at Valencia on a free transfer this summer, despite the Algeria winger's being, to say the least, something of a wild card. Oscillating between brilliance and anonymity, Feghouli could be a success or a disaster; it's certainly going to be fun finding out which.

4. Aaron Ramsey, Arsenal

International tournaments are not the best barometer for how a player will perform in domestic competition. Still, Aaron Ramsey's Euro 2016 with Wales was so impressive that one wonders what happened to him last season, having faded in the Arsenal team after such impressive previous form. Given the amount of injuries Arsenal annually suffer from, Ramsey will probably not want for time on the pitch, but where will he feature? He's capable of playing several different roles in their midfield but isn't the first choice in any of them -- an option, rather than the option. Can he harness his form for Wales and nail down something regular?

3. Raheem Sterling, Manchester City

After a disappointing Euro 2016 with England that saw Raheem Sterling widely criticised and scapegoated, it's almost easy to forget that the former Liverpool player also wasn't very good for Manchester City in the latter stages of last season. Perhaps this was a confidence issue. Perhaps he suffered from having a fairly passive manager in Manuel Pellegrini. Perhaps it was just a poor run of form. But a quick, high-intensity forward like Sterling is in theory just the man for Pep Guardiola, so it will be interesting to see whether he flourishes under his new manager's guidance.

2. Wayne Rooney, Manchester United

For England, he played in midfield. For Manchester United, it seems he will be a striker. Jose Mourinho was so dismissive of Wayne Rooney's capabilities in the middle of the park that it's impossible to see him playing anywhere other than in the forward line in the coming season. But where? Marcus Rashford and Zlatan Ibrahimovic are better options in the No. 9 role. Rooney is by no means a winger, and should the Paul Pogba saga ever actually come to a conclusion, he would be most effective in an attacking midfield role, which would affect Rooney's role. The England skipper's latter career has been a curious business all around, but seeing where he plays, if at all, this season will perhaps be even more curious.

1. John Stones, Everton

There's a lot of pressure on John Stones. In an ideal world, he would be able to play somewhere relatively quiet, work out his game's weak points, improve and then emerge at the end of the season as the composed, ball-playing defender that anyone with a stake in the England team hopes he can be. If he stays at Everton, he might have that chance, but if the colossal move to Manchester City goes through, he won't. But there is an upside, namely that he will be working with Guardiola, a man who will encourage Stones' strengths and hopefully iron out his weaknesses. If he can cope with the attention, this could be the season that makes Stones.