Wet asphalt? Detroit Locker in the rear has no effect on that, unless you have terrible tires and piss poor driving skills. Even then, quality tires go a long way in the rain.
Googling Detroit Locker in the rain gets some hits,they seem similar to what I have read over the years.
Driven correctly, with the right tires, a rear Detroit can be quite helpful. The outside tire gets to spend nearly 100% of it's grip on side bite stability since it's ratcheting free. We've used Detroit's with slicks in the rain in many race cars.
If it is ratcheting does that mean you are off the throttle? I like to apply power coming out of a corner. I have seen a lot of races, when it rains they come into the pits to switch to a rain tire.
Ice and poor quality tires and driving habits are the Detroits kryptonite. Much of those issues can be mitigated as well. I'd hate to swap gears in both axles, without at least adding a locker up front.
I have to drive in ice,snow,and heavy rain,typical Pac NW weather. I have a CAD,so unless I want to spend another couple of thousand no locker on the front.
Of course the Detroit lockers in race cars are specified by the rules. High grip can actually be a problem, and can lead to low grip when the inside tire barely touches the ground in tight turns. Uber expensive electronically active Torsen diffs are best, but aren't good for cost controlled racing. But Detroits are nearly perfect options for such.