As far as I can tell, Chicharito is literally the opposite of what Van Gaal wants from his striker! Which is exactly why he was out of the door pretty quickly -
he favours a big, strong forward who can hold the ball up and works tirelessly for the team.
Comments from Klose (a similar type of 'fox in the box' striker) show how that kind of striker struggles to adapt to LvG's philosophy:
"It was a tough time, particularly working with Van Gaal," Klose told Germany's Die Zeit newspaper.
"I didn't feel free. It was very difficult for me to fulfil his expectations. He was asking me to make runs I just couldn't see.
"I gave it all I could, but sometimes it just wasn't enough."
The likes of Klose and Toni, whilst both were big, strong, and very good at holding the ball up, were quite immobile and static with their movement. Gomez was also the same, but van Gaal adjusted his game and made him more mobile and suited for the team, hence why he became their main striker from van Gaal's 2nd season onwards there.
Chicharito, unlike Klose, Toni, and Gomez, isn't immobile, slow, and static. He's pacey, and he's constantly buzzing around, causing havoc for defenders with his movement, both vertical and horizontal. His only issue is that he can't hold the ball up under pressure, but he's also improved in that aspect with better ball control and dribbling than he had before he came to Man. Utd. Of course, we know that he's a clinical finisher as well.
Even in pre-season for us, Chicharito showed some promise. It was only in the first few matches of the season, particularly against MK Dons, where he failed to make any impact. His weakness in holding the ball still holds him back, but otherwise, he has the qualities for the role under van Gaal.
Plus, van Gaal doesn't necessarily want big and strong strikers. In his 2nd spell for the Netherlands, he favoured van Persie over Huntelaar. In AZ, he had El Hamdaoui and Ari, neither of whom were that big and strong. In Bayern, as you know, he favoured Olic over Gomez, Klose, and Toni, and Olic wasn't even much of a ball holder for Bayern. For us, he sold Welbeck, who was more mobile than van Persie and Falcao, and he even played Wilson at times even though Wilson wasn't even strong.