I'm not really concerned with either long term.
Gurriel's 2 month sample should not discount the 567 plate appearances in 2019 and 2020 when he was a well above average hitter (124 & 135 wRC+).
He's never been an on-base guy and walk rate guy, he puts barrel on baseball and gets paid to put runs on the board. Teoscar had a similar profile before his breakout, these type of bats are just more susceptible to wild swings in production. The approach has looked a bit off to start the season, but he's shown flashes of putting it together since the Atlanta series he's batting .303/.294/.394 which isn't great but better than his horrible start in April.
With Biggio the expectations aren't that high. He's an extreme plate discipline guy with below average bat to ball skills, and just enough power to occasionally run into one. He isn't the only flyball hitter with an extreme uppercut swing, it has worked for other guys. He just doesn't quite have the power to consistently drive it 400 ft +, but he's learning to hit it opposite field and hunting for better pitches to hit. He'll eventually figure it out, that eye is too good and we need his left handed bat in the lineup. The biggest caveat with Cavan is we don't have a position open for him, he has never been a reliable third baseman. 2B/RF serviceable but neither spots are really open under the current roster construction with everyone healthy.