La Liga and Spain expert says Costa's form at club-level for Chelsea is a contrast to his performances internationally because of the different system.
Chelsea star Diego Costa may stand alone when it comes to striking effectiveness in the penalty area as the Brazil-born Spaniard is seemingly surpassing his extraordinary performance-level at Atletico Madrid last season, but the 25-year-old has struggled to make as big an impact during international matches.
For Spain expert Guillem Balague the answer may be quite simple.
"The major talking point is over the form and fitness of Diego Costa," he recently wrote in an article for Bleacher Report.
"Jose Mourinho has insisted for some time now the striker is not fully fit and certainly not up to playing two games a week. Del Bosque - not unnaturally - has responded that the player himself and the Spanish medical team are more than capable of ascertaining Costa’s level of fitness, and the last thing he would do is play a player who was not 100 per cent.
"Meanwhile, the rest of the Premier League must be scratching its head and thinking if this is a below-par phenomenon they are having to face on a weekly basis, what on earth would he be like at full throttle?"
However, Balague implies that Costa is struggling to replicate his prolificacy for Spain because he is not accustomed to the passing style. There has been little adaptation to make from Atletico to Chelsea as the strategies of Diego Simeone and Mourinho are not dissimilar.
But Del Bosque operates alternative tactics.
"Costa—despite scoring for fun at Chelsea with the assistance of club and country team-mate Cesc Fabregas—has hardly set the world on fire since lining up with La Roja… but that’s probably more to do with the system played by Spain, rather than the player himself," Balague noted.
Considering how productive the Fabregas - Costa axis is at Stamford Bridge, surely it would be beneficial for the international team to have the side built around these two players rather than hope they can fit into a system that proved to be dying out at the 2014 FIFA World Cup, when the once mighty Spain were eliminated from the tournament after just two group games.