I don't think anyone disagrees with this. Yet, for completeness, we should dissect the numbers.
Per the Steamer projections, Bell's Steamer projections are 15.1 OWar and a -15.9 DWar to bring it down to 2.0 projected. This is similar and slightly better than Naylor's projection for 3rd on the team behind Ramirez and Kwan.
I was a bit surprised by Rosario's WAR not really the 3.4 which is 4th on the team (before Bell) but its broken down to 5.7 oWar (which is 6th on team following Oscar's 10.3 oWar proj and just ahead of Brennan's 3.4 oWar with 1/3 of the ABs) and Rosario had a whopping 6.4 dWar.
And, if we just go on projections alone, Freeman's 92 AB proj bumped by a factor of x6 to get closer to Rosario's 640 AB, he would be 3.6 oWar and 1.8 dWar for about 2.4 overall War. Arias had worse projections so I used Freeman as winning 2B.
So, yes, Rosario > Freeman still (especially as Freeman would have more even splits versus Rosario's skewed splits). But, FO is looking at it as ...
(1) They need to bring the young-lings up at sometime and it maybe the perfect time for Freeman/Arias to duke it out for a starter role (as Kwan got on day 1 last year).
(2) Freeman/Arias won't be as great per se as Rosario but it is not a huge drop off (as the hot bat will win the battle)
(3) Even if no one really stands out, by September, you have Rocchio/Tena/Noel banging on the door to replace Rosario's #s.
(4) And per analytics, righty/lefty splits do not matter much in regular season -- only in playoffs for true team-on-team matchups.
Abreu would have been prefect but he choose Houston due to better roster/WS run. But, there were guys like Myers with better splits than Bell (for true right matchup). Yet, they went Bell as #s department says to go with the better overall bat especially as you face many more righties during the year and is why we have soo many Lefties or switch hitters in our system compared to other teams (it is how the Guardians build their roster). This board angst about LHP isn't the top priority for the FO.