Timid to me is avoiding the fight when you're at least co-E and there's no major disadvantage in numbers. 'Fighting' might involve BnZing the lower con to death and keeping him down so he can pretty much never get a gun solution on you. To me that's not timid, that's using the situation to your advantage. It's the low con's job to equalize the E if he can.
I'll second the sentiment that people are usually running from the 3 guys that are higher than the two of you coming in on the fight. That's what I'm usually extending from when I do extend. Either that or the enemy is in a co-E plane that can turn better than mine, and has demonstrated that he knows how to use it.
As to 'plateauing' in skill level, I don't exactly see it as that. You're just refining one skillset instead of another.
Like it or not, engaging multiple cons with advantage, killing a few of them while keeping your advantage, and RTBing is a skill set. Gunnery at high speeds, often compression speed against slower more maneuverable aircraft isn't that easy. Maintaining your E while still applying enough pressure to the enemy to keep them off balance takes skill. Sure, if you do it right and the enemy aren't working together to get you it's 'easy' compared to engaging those same cons in a dogfight.
Dogfighting is another skill set. It requires you to have better skill at avoiding the enemy's guns, and the ability to handle your plane in low-E states. Most of the time in the arena I see it as 'begging to get shot by the fifth con you didn't see that is BnZing the furball' but that's just me. These are the whiteknuckle fights if you don't get BnZed early.
I've known quite a few guys who were outstanding in a turnfight that couldn't maintain their advantage past two turns if you put them in a fast, less maneuverable plane and gave them a world of enemies below them to shoot at. I've also seen a lot of guys who could beat you down six ways from Sunday in an E fight if they start with advantage who can't deal with a con co-E 800 yards out on their six.
Bleh, the 'plateau' discussion is starting to feel dangerously close to a hijack. Bottom line, if someone's running from me when I have advantage, they're timid. If I'm running from someone who has advantage, I'm flying smart. So nyah.
Wiley.