Is there a more thankless task in football than the role of second choice goalkeeper? This marginal figure watches from afar as his team triumphs or toils, resigned to the fact that even if they achieve success his contribution was little more than that of a cheerleader observing from the comfort of the substitutes' bench.
What little action one does experience comes thanks to the misfortunes suffered by others; an untimely injury or suspension perhaps, or else a run-out given almost out of pity in a cup clash of secondary importance. It takes a special temperament to accept this fate, which seems to contradict the very raison d'etre of a professional football player: that of actually playing the game of football.
In 2018 the 32-year-old's prospects became even dimmer. Thibaut Courtois's arrival relegated Casilla to third choice at the Bernabeu, reducing his chances of first-team football to that desperate grey area between slim and none. But the goalkeeper now has a new chance to shine: under the watchful eye of none other than Marcelo Bielsa, making waves with Championship leaders Leeds United.
Casilla has now completed a move to Leeds on a free transfer, signing a four-year deal. It represents the first transfer business of the window for Bielsa, who has worked wonders with a side that has been completely transformed by the eccentric Argentine – spy scandals notwithstanding.
One need not be an international master of espionage to see why the experienced shot-stopper has caught Bielsa's eye. Throughout his career Casilla has forged a reputation as a solid, no-frills custodian, rarely putting a foot wrong between the posts despite his limited first-team action over the past few years.
The influence of Madrid great Zinedine Zidane, moreover, has helped improve Casilla's ability on the ball, making him an adept distributor and thus a perfect fit for quick-passing, high-pressing Leeds.
From Leeds' point of view too, the addition of an internationally renowned keeper is a logical step. Current No.1 Bailey Peacock-Farrell is just 22, and while the Northern Ireland international has come on in leaps and bounds he is still prone to bouts of inconsistency and the occasional disastrous mistake.
Bielsa had hoped to keep the pressure on Peacock-Farrell through deputy Jamal Blackman, a former England youth international and one of Chelsea's immense army of loanees that criss-crosses the football world. Blackman, however, was forced to return to Stamford Bridge in November after breaking his leg in an Under-23 match, a bitter blow for the player who, as Bielsa admitted, was on the verge of pushing his way into the first team.
Casilla will arrive not as Peacock-Farrell's deputy but as direct competition for a starting spot. The prospective move has already won the approval of one former Leeds favourite. “He has got a wealth of experience, hasn't he?” Noel Whelan signalled to the BBC .
“He has been at one of the biggest clubs in the world. Look, if that’s going to be happen, it’s fantastic. We need strength in depth in that area.”
Leeds are also looking forward. If the Whites can repeat their brilliant form over the first half of the season and clinch a much-desired return to the Premier League, a goalkeeper of Casilla's stature and experience will be invaluable in one of the world's most demanding divisions.
For Casilla, Elland Road represents an intriguing challenge. The player has been possibly football's most privileged spectator over the last four years, generally looking on from the sidelines as Madrid have won three consecutive Champions Leagues. Those medals hang proudly over his mantelpiece, even if it was Keylor Navas who wore the gloves.
At Leeds, however, he will have the opportunity to show the brilliant form week-in, week-out that convinced Madrid to take the former Blancos trainee back to the club after shining at Espanyol. Both Casilla and Leeds have everything to gain from such a partnership, as Bielsa's boys go all-out for a return to the promised land of the Premier League over the next few months.