Does a bad first baseman like Hanley only start 4 of the 6 last year? It just makes so little difference over the course of a season is the main point.
Here are the numbers for selected first baseman from the Fielding Bible stats on billjames.com:
Moreland:
2017: +11 runs, 5/14 on possible DPs.
2016: +7 runs, 5/17
2015: +4, 4/8
Hosmer:
2017: -9 runs, 1/9 on possible DPs
2016: -15 runs, 8/18
2015: -3, 6/15
Hanley:
2017: 0 runs, 0/0 on possible DPs in 146 innings played
2016: -4 runs, 3/7
Goldschmidt:
2017: +7 runs, 6/11 possible DPs
2016: +2 runs, 17/27
2015: +17 runs, 10/19
Rizzo:
2017: +11 runs, 10/25 possible DPs
2016: +13, 9/20
2015: +8, 6/15
Votto:
2017: +14 runs, 9/13 possible DPs
2016: -15, 6/26
2015: +5, 11/22
Gurriel:
2017: -3 runs, 10/16 possible DPs
Zimmerman:
2017: -8 runs, 4/10 possible DPs
2016: -1, 3/5
2015: -3, 6/8
Cabrera:
2017: -5 runs, 5/17 possible DPs
2016: -10, 15/24
2015: +4 runs, 6/13
Davis:
2017: -2 runs, 8/21 possible DPs
2016: +5 runs, 8/13
2015: +3, 5/14
They have Moreland's +11 runs last year tied with Rizzo for second in this group, behind only Votto. But they have Votto as a terrible -15 runs in 2016. By these stats, Moreland is one of the best defensive first basemen around over the last 3 years, despite not being particularly great at converting DP opportunities.
FB scored Moreland as +3 going to his right, +5 straight on, and +2 going to his left last year, and +11 on grounders, +1 on balls in the air, with the +11 runs overall. So positive in all areas, no real weaknesses, very good overall.
Interesting that FB has Hosmer as one of the worst defensive first basemen around-- much worse than Hanley was in 2016, for example. I wonder if the Red Sox use fielding numbers that are similar to these.