Lionel Messi has been the best performing forward in Europe's elite leagues in 2015, according to a CIES Football Observatory study, while it ranked Cristiano Ronaldo only 29th among forwards.

The CIES study assessed players in La Liga, the Premier League, the Bundesliga, Ligue 1 and Serie A according to six Key Performance Indicators (KPIs) -- shooting, chance creation, take-ons, distribution, recovery and rigour.

Barcelona star Messi, who has scored 17 goals in La Liga since Jan. 1, rated as the most effective forward, with teammates Luis Suarez and Neymar also placing highly at fourth and 12th respectively.

Messi's closest competitors were Bayern Munich star Arjen Robben and Wolfsburg's Bas Dost, who netted 11 goals in six Bundesliga games following the winter break but has not scored since.

Real Madrid forward Ronaldo, though, has scored only six La Liga goals since the turn of the year and ranks 29th, while the other members of the European champions' "BBC" attack were even lower. Gareth Bale, who has faced heavy criticism for his recent form, is 35th and Karim Benzema is 37th.

Chelsea's Eden Hazard and Arsenal's Mesut Ozil were rated the joint-best attacking midfielders, with Manchester City winger Jesus Navas in third place.

Highly rated Wolfsburg midfielder Kevin De Bruyne, who has been linked with a big-money move to clubs including Bayern Munich, is close behind in fourth; Borussia Dortmund's Japanese star Shinji Kagawa is ranked fifth after a recent upturn in form.

Dortmund's Nuri Sahin, meanwhile, also helped Jurgen Klopp's men to four successive Bundesliga victories before picking up an injury in late February and is ranked the top central/defensive midfielder, with Juventus' Paul Pogba and City's Fernandinho in second and third respectively.

City left-back Gael Clichy is the highest ranked full-back by some distance, with Madrid's Marcelo and Bayern's Rafinha in second and third.

Bayer Leverkusen's Emir Spahic is the top-rated centre-back, followed by City's Martin Demichelis and Dortmund's Mats Hummels. Manchester United's Chris Smalling is fourth on the list, with Paris Saint-Germain pair Thiago Silva and David Luiz taking fifth and sixth respectively.

KPIs (weighted according to player position)

- Shooting: ability to take advantage of goal opportunities through accurate shooting

- Chance creation: ability to put teammates in a good position to score

- Take on: ability to create dangerous situations by successfully challenging opponents

- Distribution: ability to keep a hold on the game through efficient passing

- Recovery: ability to minimise goal opportunities for opponents through proficient interception work

- Rigour: ability to minimise goal opportunities for opponents through robust duelling