Why pulling a chain attached to a tree stump that went over a mound of dirt in between caused rear bumper to bend upwards?

I know this might sound like a really stupid question. but I had read online that having something for the chain to "go over" in between while pulling it out of ground would give it more leverage from an upward angle and was told that this upward pulling (instead of straight forward) would cause the stump to come out much easier since pulling up is best. but INSTEAD what happened is it bent my bumper upwards. ******************** so should I be able to bend the bumper brackets back straight again by pulling with chain attached to a lower point ? (like not pulling it over a mound of dirt this time, but make sure the chain is at a lower point? I mean in that case it would bed it downwards?)