2. Lesnar loses

One of the big risks WWE would assume in letting Brock Lesnar carry the Universal Championship into a UFC fight would be the chance of him not only losing, but losing in such a way that diminishes WWE’s credibility. While most fans understand wrestling works on predetermined outcomes, it would nonetheless be more difficult to buy Lesnar as an unbeatable monster in WWE if he were, for example, to tap out or get knocked out in the first round of a high profile MMA fight.
While UFC would probably rather not have its champ lose in a WWE ring either, it’s understood that would be less Lesnar's fault than Vince McMahon’s decision, besides which mechanisms like outside interference allow for a more thoroughly protected loss in WWE.
Breaking Vince Russo and Jim Cornette update HERE.
Having Lesnar drop the title at WrestleMania would both protect the Universal Championship in the long term and add a nice feather to the cap of the guy who beat him for not only having won a top title but also pinned a UFC champion.
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