Yes, but my opinion is not based on wild speculation. fWAR is greatly affected by PAs and hos well you play your position.
Alonso is a really bad defender at a position not highly valued by fWAR.
Contreras used to be a catcher (a higher valued position than 1B) but now plays 1B. He seems to be a better defender at 1B than Alonso, and should get more PAs than he used to get as a catcher. He had his career high in PAs in 2025- his first year at FT 1B. His last 4 years of fWAR were influenced by being a catcher, but since he had less PAs due to catching, I think his WAR numbers can be similar. 3.5>2.8>2.7>2,8. It looks like Fenway might help him, so an estimate or 2.8 to 3.0 seems reasonable. Three year average: 2.8
Alonso's last 4 seasons: 3.8>2.8>2.1>3.6. It's harder to project his final 2026 numbers due to a wider range of recent production, but his 3 year average is 2.8.
Yes, it's early, but they've been very close for 3 years.