Why did Toriyama change Yajirobe's character so much in DBZ?

[DBZAOTA482]

He was never such a sniveling lazy coward in Dragon Ball. I mean, he was still belligerent glutton but he was a great fighter, an experienced swordsman, and pretty badass when you think about it.

Then come DBZ, he wants nothing to do with the Z-Warriors. He refused to train to fight the Saiyans... he had to be forced by Korin to join the others and in the one panel that shows him training he was sitting on the floor praying implying he wasn't taking the training anywhere near as seriously as the others. He never bothers even showing up to the battlefield... he just hides in the mountains.

Now before you say he was scared shitless of Piccolo Daimao... but his fear was pretty normal. To him, Piccolo Daimao was like the boogeyman to him. Not to mention he was far more willing to help out during the whole situation than he was of the Saiyans... he even climbed Korin's tower with Goku on his back. DBZ Yajirobe would only help out at the last second.

Yajirobe was also willing to participate at the 23rd Budokai despite the odds being against him.

Why did Toriyama change him like this? Did he realize he made Yajirobe too powerful and made him into comic relief so he wouldn't have to write him?

 

[Let's Go Fearless!]

Perhaps because there alot of Z fighters and new characters were introduced [Vegeta, Gohan and Farmer shotgun] and AT was developing their characters which makes Yajirobe irrelevant.

 

[Zippy]

Probably because of how his charcter looks visually. A fatass. It suits him.

 

[Warmmedown]

AT didn't do him justice. How did a usually lazy human get so strong? I would like to see his backstory.

As far as staying back against the saiyans maybe he thought he wasn't strong enough or that aliens are scary. Climbing Korin Tower was a less complicated to think about thing than fighting the saiyans so he may have just thought he'd be out of his depth and wanted to wait in the shadows for a chance to help. Excuse making for AT though.