I don't know and I can't be arsed to look it up but by Phil's age he'd figured in a similar amount of games with the main differences being that he was trusted to start league games, had played in a Champions League final and was well on his way to figuring in a second.
That's playing as a defender too which is a much, much bigger risk than someone in Phil's position. They trusted him because he showed the talent early on. Phil showed the talent and we just said "okay, cool, but there's an imaginary pecking order where you'll have to wait your turn regardless of whether or not the ones ahead of you stop performing".
Same goes for Garcia. Nobody can say with a completely straight face that Otamendi and Stones should be anywhere near the team on merit. They're total fuck ups and they have the knack for undoing everything the team has been holding onto by inexplicably fucking right up in moments where basic common sense should apply. Garcia came in, looked solid and composed and he just gets shunted to the back of the pack because he's younger than everyone else.
And that's not even to say he's been perfect because he did make a few mistakes but those were nothing more than wrinkles in need of ironing out. .
Now you're telling me that we don't have time to "experiment", by which you presumably mean to let both of them gain experience. Of course they don't! They've had months for that but the manager has denied then every reasonable opportunity to make the step up. It's entirely his fault that they aren't perceived to be ready for bigger games.