Because he has a rank rating of 9, while Leadfoot and Topspin have 5 and 4, respectively? "BRING DOWN DAT PILLAH!" Though honestly, the wreckers pretty much seem to be of one mindset, so they really don't need somebody barking orders because they're always on the same page.
Those things are about as accurate as my fanfic is. Besides, the OP specified "bases solely on the movie". Even counting that occasion, Leadfoot is much more strongly implied as the leader of the Wreckers, as you can see that "Wreckers, KILL IT." and "WE'RE LAUNCHING AT DAWN!" sounds much more leadership-like than "BRING DOWN THAT PILLAR!". I like Roadbuster too, but I see nothing wrong with him being Leadfoot's badass right-hand man.
roadbuster, he explained everything and stood for what they were. Leadfoot said "wreckers kill him " as a join in libe of, I'm going to do it, join in. Roadbuster was calling the shots
Both Roadbuster and Leadfoot were seen barking out orders to humans, so I don't really know. Leadfoot said that they were launching at Dawn, but that seemed more directed as a "hurry the hell up" to the other Autobots instead of an order. Also, the "Kill it!" line seemed like a given. Personally, I think they all just kinda cooperate.
Roadbuster is leader of the Wreckers in the movie....for that set of Wreckers....and his toy basically shows that with his stats being a Rank of 9.
Leadfoot is the leader. Roadbuster sometimes acts like he's the leader because he has a wee bit of a problem knowing when to keep his mouth shut. Also, keep in mind the order in which we usually saw the Wreckers in alt mode. It was always Leadfoot, Roadbuster, Topspin - 1,2,3. Oh, and Topspin is the cute one.
Leadfoot is the lead wreaker because when they are in Chicago, he is the first to battle and gives the orders, Roadbuster is just 2nd in command. Leadfoot is the leader no doubt.
To all you loons saying the toy's stats prove Roadbuster is the leader of the wreckers, If these stats are accurate how come Ironhide has a Skill level of 5. and Starscream has an intelligence level of 5. If anything the toy stats should mean the opposite of what you all say, making Topspin the leader.
Leadfoot, because he's voiced by John DiMaggio, he gave orders, and he's large and in charge. I say Roadbuster is his second in command, leaving Top Spin as their strong and silent third wheel.
honestly....who cares who is the leader....they all have input and they all will obey Prime being they know he is there hope of beating the cons....at the end of the day...its your Transformer world....you can say and make whomever bot you want commander of the Wreckers....Til all are one... A.J.