Start with the fact that they played in Cactus League ballparks, where there is usually far more offense and power production than there is over in Florida. They are good places to hit, not the dead zones of say Roger Dean. Second, consider that some of the pitchers had logged full seasons and were pushing through a month they've never pitched in before -- after some of them had missed an entire 2020 season. To me, sharp pitchers stood out for success there because of that.
All that said, it's good to show what they did relative to other hitters, and Nootbaar and Yepez stood out when compared to what their peers were doing. Look at strikeouts vs. walks. Look at extra-base hits. Teams are going to look at exit velo and hard hit, and clearly both of them were rewarded with fortune for hitting the ball hard and hitting it hard often. They stood out relative to the other hitters who had all of the factors mentioned above working for them, too.
Still, a pitcher who did well in the Arizona Fall League, to me, looks all that much better because of the hitting environment where he did well.