Bale is at the Santiago Bernabeu because of Perez. The winger, since day one, has been seen by Perez as Cristiano Ronaldo's eventual successor. When Real and the former Tottenham star were in the middle of their dramatic drop in form in March, Perez called a media conference. But it wasn't to reject criticism of the coach or the team - it was to defend Bale.
While recognising Bale could be doing better, Perez hasn't been caught up in the over-the-top criticism of his €100 million signing. He knows Bale is still playing the role he's been asked - that is as second fiddle to Cristiano Ronaldo.
The La Decima apart, if there is anything Perez would like to define his presidency, it would be for Bale to emerge as the game's No1 player. After being blocked by Santos from signing Neymar ahead of Barcelona, Perez shrugged it off, happily informing disappointed directors that "Bale will be our Neymar".
Ronaldo arrived at Real already a Champions League and Ballon d'Or winner. For Perez, Bale is a different case. For the man who created the Galacticos, there's nothing he'd love more than to see the Welshman win the Ballon d'Or as a player he had personally identified and brought to the Santiago Bernabeu.
Next season, Ronaldo will turn 31, and there is concern inside Valdebebas that his powers are waning. Arrigo Sacchi, the former Real general manager, expressed as much this week. Perez knows he'd be hard pressed to find a better heir to Ronaldo than Bale.
There's claims if Carlo Ancelotti leaves at the end of the season, Bale will follow him. But the Italian isn't close to the winger. His No2, Paul Clement, handles the day-to-day management of Bale, even translating Ancelotti's team instructions to him in English.
If the former Chelsea manager is sacked, it won't matter a jot to Bale.
Then there's the new Adidas tie-up with United. It's suggested the German sportswear giants would love nothing more than to celebrate their partnership by delivering Bale to Old Trafford.
But Real also are an Adidas partner - they've been together for 15 years. The idea that they'd actively seek to remove one of their stable's stars from their richest and most successful client seems far-fetched.
And we're also not taking into account the player, himself.
Is the Welshman really willing to up sticks and return to the UK with his tail between his legs? Last season, with his goalscoring stamp on both the Champions League final and Copa del Rey, Bale was one of the great stories of the campaign.
At the beginning of his Madrid career, he was portrayed as 'little boy lost'. He was criticised by a local media and mocked by a popular comedy show. Yet by the end of the season, with two trophies under his belt, Bale was being celebrated by the same people who had pilloried him months before.
Against Juventus on Wednesday night, Bale appeared a man riddled with self-doubt. But he's been here before - and come out the other side.
Whether he does that at Real, United or elsewhere will be Perez's call. But when you're talking legacy and history, it's difficult to imagine the Real president happily accepting defeat when it comes to his record signing.