These new left-handed hitters join a lineup in which three of the best four returning hitters on the team are lefties—Robinson Cano, Kyle Seager, and Seth Smith. The result of all these moves is a lineup that leans very heavily to the left-handed side.
The following chart shows the Mariners current lineup according to MLB Depth Charts. There is a column for how these hitters have done in their career against each handed pitcher. The AVG/OBP/SLG column shows each hitter’s batting average/on-base percentage/slugging percentage. The metric wRC+ is from Fangraphs.com. This is a rate statistic that credits a hitter for the value of each outcome (single, double, home run, etc.) and makes an adjustment for the park the player plays in and the run environment. A wRC+ of 100 is exactly league average, so a wRC+ of 125 means a player created 25% more runs than a league average hitter would have in the same number of plate appearances. The players highlighted in light blue are those who are likely to be platooned, meaning they will most often play against pitchers who throw with the opposite arm.
That being said, it’s not all chocolates and roses. These are career statistics, so they may not accurately represent who these players are heading into the 2016 season. Robinson Cano has likely seen his best days and is no longer the hitter he was when he was in his mid-20s. Nelson Cruz will be 36 and is likely to decline. Shawn O’Malley has a very short major league track record, so his career statistics consist of a small sample size. Jesus Montero hasn’t come close to reaching the potential the Mariners saw in him when they acquired him in a trade with the Yankees years ago. Franklin Gutierrez hasn’t played a full season since 2010.
The following chart shows the Mariners lineup and their 2016 Steamer Projections from Fangraphs. The Steamer projections don’t separate projections based on the handedness of the pitcher, so these are overall projections. The Mariners ability to platoon should make some of these lineup spots more productive than they would be with just the main starter listed. The weak links in the lineup are at the bottom at catcher, centerfield, and shortstop.
With that in mind, the option I think is interesting is Steve Pearce. Pearce played first base, second base, left field, and right field in 2015 and played 10 games at third base back in 2011. He’s not a great fielder, but he can hold his own. He was an above average hitter in 2013 and 2014 but struggled last year. In his career, Pearce has hit much better against lefties but not terrible against righties. His 2016 projection suggests he’ll be an above-average hitter overall.