Yikes.
The Jays knew there was a strong likelihood that Semien would only be a Blue Jay for 1 year. Why on earth would you hamper Bo's defensive development at SS by moving him off the position for 1 year, especially when Semien isn't 'miles' ahead of him defensively? Is Espinal better than him as a SS? Maybe, but I'm not 100% convinced he'll be a major league starter for the next 5 years (I love what he's been for the team, but he may get more and more exposed as a full time player. He hits lefties well, but righties are killing him. A platoon with Biggio may be our best bet in the playoffs).
I know defensive values are challenging and iffy, but Bo's defensive value this year is already more than it was last year and is ahead of guys like Trea Turner, Tim Anderson and Kiner-Falefa. It often takes SS's time to develop defensively and for a 24 year old, Bo is holding is own. You think KC should move Witt Jr. off SS too?
I can't say I disagree with moving Bo down in the lineup a bit more, but I do trust the Jays know what they are doing and know what's best for Bo and the team.