Isco has yet to start a La Liga fixture under Solari, and on several occasions the Spaniard has failed to make it onto the pitch at all.
So far there has been no explanation from the manager over his reluctance to use Isco, even as Madrid have struggled to string together a good run of results, falling 10 points behind league leaders Barcelona.
Isco actually did start one of Madrid’s more shocking setbacks, the 3-0 Champions League defeat to CSKA Moscow – Madrid’s worst-ever home defeat in the competition.
And though Van der Vaart acknowledged that Isco has had problems with managers before, recalling the times Zinedine Zidane left him out of the XI for long stretches, the recent selection issue bothers the Dutchman.
“It’s crazy for me, he is the best player in the world,” Van der Vaart told Marca.
“But, he always has problems with coaches and even [Zinedine] Zidane never trusted him 100 per cent.
“When I go to watch Madrid I’ll see if he starts and if not, I’m going home.”
Santiago Solari admits his Real Madrid side put in a “weak game” as they lost to Leganes – but was pleased at securing a place in the quarter finals of the Copa del Rey nonetheless.
Solari made only four changes from the La Liga victory at Real Betis on Sunday as the likes of Keylor Navas, Raphael Varane, Casemiro and Vinicius Junior all started the 1-0 loss at the Estadio Municipal de Butarque.
A Martin Braithwaite tap-in on the half-hour mark was enough to seal victory for Leganes on the night but it is 19-time winners Real who progress into the next round, even if Solari was not pleased with the display.
“It was a weak game, especially in the first half,” he said after the match.
“We got through and we gave the players who needed it their minutes. I didn’t think we were in any danger of being eliminated.”
Substitute Brahim Diaz hit the post late on for the visitors but it was a poor performance from a team out of form.
When asked why his side had struggled, Solari replied: “Sometimes you try things and they don’t work, so you have to change it.
“We lacked depth and struggled because we didn’t have a real focal point in attack. I changed things at half time in order to improve the match.”
Real host Sevilla on Saturday looking to keep up winning ways in La Liga where they sit fourth, 10 points adrift of leaders Barcelona.
Manchester United midfielder Juan Mata has backed former Valencia teammate Isco – who is undergoing a rough period under Santiago Solari – to bounce back from the series of setbacks.
Isco has not started a single league game under the new manager and there is no evidence to support any claim that things might get better for the Spaniard at Real Madrid.
Mata praised Isco’s talent and said that he believes things will improve for the former Malaga man.
“I appreciate Isco, as I met him at Valencia and I saw all the talent he had,” Mata said in an interview with Radio MARCA.
“The only thing you can do in situations like this is to continue working, to not lose confidence in yourself and to try to take advantage of opportunities when you have them.
“In the end, talent always stands out and he has plenty of it.
“I send a very strong hug from here and I’m sure that, in the end, things will improve.”