You can easily build an offense from center field if that is where your hole is.
This all assumes that Bell from the first half is Bell going forward. That is far from assured. Tellez has a wRC+ of 118, basically average 1B play which is a win for Stearns in comparison to prior years. Bell has an wRC+ of 147. That is a big difference. However, The Brewers aren't getting those PAs, they are getting future plate appearances.
All projection systems have Tellez maintaining that 118 wRC+ going forward. The projection systems are all over the place for Bell, ranging from 121 wRC+ which is indistinguishable from Tellez to a 140 wRC+ which would be an improvement. Now this range isn't that surprising given Bell has a BABIP of .331 compared to his career of .291. And Bell's career wRC+ is 118. But the idea that Bell is a sure fire upgrade is not supported, especially when defense is considered.
We have seen Bell have amazing first halves before where it looked liked he broke out to an MVP level only for him to crash in the second half. See 2019.
Bell is available and obtainable whereas some of the CF options that should be available (Mullins, Reynolds, and Garcia since they are on the wrong side of the age curve for rebuilding ) will likely not be obtainable for the Brewers. I just think Bell and Mancini as well are not the needle movers people think they are.