SEATTLE -- As Spring Training draws closer, the Mariners still have quite a bit of roster clarity to settle, with Friday marking the next big date on their offseason calendar. It’s the deadline for clubs and their unsigned arbitration-eligible players to exchange salary proposals for the 2021 season.

The Mariners have three such remaining players -- shortstop J.P. Crawford, reliever Rafael Montero and catcher Tom Murphy -- and all figure prominently in the club's plans for 2021.

• Offseason checklist: Mariners' needs, moves

Here’s a breakdown for what’s at stake:

What is salary arbitration?
Players with three or more years of MLB service time but fewer than six (when they qualify for free agency) can negotiate their salaries for the upcoming season, which are primarily based on comparable players who have signed contracts in recent seasons. The player and the club will each present a salary figure no later than Friday at 10 a.m. PT.

If the player and club cannot agree to terms, then a hearing is scheduled in February, when a panel of arbitrators, who, after hearing arguments from both sides, selects either the salary figure of the player or the club.

Players and clubs can continue to negotiate salaries between Friday and a potential hearing on a one- or multiyear deal, which is typically how these negotiations settle.

Which Mariners are eligible for arbitration?
Right fielder Mitch Haniger reached an arbitration-avoiding agreement on Dec. 7 for the same rate that he would’ve earned in 2020 before prorated salaries trimmed his pay to $1.1 million. Given that Haniger hasn’t played in a big league game since June 2019 due to a series of injuries and surgeries, he wasn’t projected to earn a pay bump.

Here is a breakdown of the other three Mariners up for arbitration, with what arbitration year each is entering and their projected 2021 salaries, according to Cot’s Baseball Contracts.

• SS J.P. Crawford (first year, $1.9 million projected)
Crawford is one of 19 big leaguers who reached Super Two status this offseason and thus is able to enter arbitration early, having accumulated two years and 163 days of service time over parts of four seasons. Typically, Super Two applies to players with two years and at least 130 days of service time, though the cutoff date varies.

Crawford, who turned 26 on Monday, is coming off a season in which he slashed an improved .255/.336/.338 with two homers and 24 RBIs, and he was worth 1.1 wins above replacement, per FanGraphs. More chiefly, he overcame his defensive struggles and won his first Gold Glove Award. Crawford’s 2020 salary before proration was $575,800, per Spotrac.

• RHP Rafael Montero (second year, $1.7 million projected)
Acquired in a trade with the Rangers on Dec. 15, Montero is due for a pay bump from the $785,000 pre-proration rate he earned in 2020, when he compiled a 4.08 ERA in 17 2/3 innings across 17 outings, with eight saves in eight opportunities. He is the early favorite to earn the Mariners’ closer role among a bullpen that Seattle will likely add to before Opening Day.

• C Tom Murphy (first year, $1.3 million projected)
Murphy missed the entire 2020 season due to a broken bone in his left foot, an unfortunate setback after he was arguably the Mariners’ best offensive player in ’19, when he led the club with 3.2 WAR and hit .273/.324/.535 for an .858 OPS and 126 wRC+.

The sixth-year veteran will enter 2021 as the starting catcher, though he figures to split time with Luis Torrens, who was acquired from the Padres at the Trade Deadline and performed well after. Pre-proration, Murphy was slated to earn $577,300 last season, slightly more than the MLB minimum, so he’s up for a decent raise.

How often do cases reach arbitration?
It hasn't happened since general manager Jerry Dipoto took over after the 2015 season. And only twice since 2000 has Seattle gone all the way to a hearing -- in '15, when reliever Tom Wilhelmsen lost his case requesting $2.2 million and the panel choosing the team’s $1.4 million offer; and in ’03, when starting pitcher Freddy Garcia won his case for $6.875 million over the team's $5.9 million offer. The Mariners have had 20 cases go to a hearing in the franchise’s 43-year history, but 17 of those were from 1980-93.

How will arbitration negotiations affect the rest of Seattle’s offseason?
They shouldn’t at all. All four arbitration-eligible players were already part of Seattle’s 2021 plans and, regardless of how the three outstanding settle, they should come at an economical price.

The club’s most glaring needs are in the bullpen, which posted an American League-worst 5.92 ERA last season. And if it hopes to sustain a six-man rotation, as manager Scott Servais said last month, Seattle will likely need to shop for at least one more innings-eating starter.

• Hot Stove Tracker

Including the arbitration projections from Cot’s, the Mariners have just under $64 million committed for their 26-man roster, with room to add. That’s way down from their $146.5 million from ’19, before the economic situation caused by the pandemic and with many high-price obligations still on their books. 

But despite the financial flexibility for ‘21, don’t expect Seattle to make a free-agent splash. Dipoto has said publicly that the club won’t shy from executing a high-profile deal over the course of the rebuild, but not until the club is closer to contending -- and the Mariners aren’t yet in that market.