DETROIT -- The Tigers' flurry of moves to shed players from their 40-man roster this month wasn't just about cutting ties with players who struggled in 2017. It's also about opening space for prospects they hope can be part of the team in the years ahead.
For the first time in several years, the Tigers have a decent-sized crop of prospects that could be left open to next month's Rule 5 Draft unless Detroit adds them to its 40-man roster. The group doesn't include Detroit's top prospects, but with seven members of MLBPipeline's top 30 Tigers prospect rankings, the Tigers have some decisions to make ahead of next Monday's deadline to finalize rosters.
The Rule 5 Draft allows teams to select players from other organizations who aren't on their club's 40-man roster. Teams invest $100,000 to make a selection, who must remain on the Major League roster the entire season or be offered back to their previous club for $50,000. Players drafted or signed at age 18 or younger are eligible after five Minor League seasons. Those drafted or signed at an older age are eligible after four Minor League seasons.

The Tigers used the Rule 5 Draft to their advantage last offseason by selecting lefty reliever Daniel Stumpf, who became a regular in their bullpen by season's end. His 55 appearances ranked third among Tigers pitchers behind Shane Greene and Alex Wilson.
Detroit currently has 31 players on its 40-man roster. The team will need to keep at least one open spot if it wants to select anybody in the Rule 5 Draft, a pretty good possibility considering Detroit holds the top pick. Any free agents signed to Major League contracts before the Winter Meetings would also require a 40-man spot, though the Tigers are unlikely to dip into that end of the market until later in the offseason.
In many cases, the decisions with Tigers prospects aren't simply about how much the team values them. The decisions also involve the likelihood that another team would take a chance and draft them, then keep them on their roster all year. Historically, teams are more likely to use Rule 5 to find a reliever they can stash or a versatile bench player they can play in spots.
Among the ranked Tigers prospects that could become eligible are:
OF Mike Gerber (ranked 10th): The Tigers have just three outfielders on their 40-man roster after cutting ties with Tyler Collins, Alex Presley and Jim Adduci. Detroit will add some depth on Minor League deals, but Gerber's left-handed bat and defensive versatility provides in-house depth now and a potential long-term fix later. The 25-year-old has played in just four games above Double-A Erie, finishing the season in Toledo following September callups. But with a .290 career batting average and .834 OPS in the Minors, he's on a track to reach Detroit next year.
LHP Gregory Soto (12th): Soto would be a reach for another club to try to keep on a Major League staff after just five appearances above Class A ball, but his breakout 2017 season and lefty arm could interest in a team in full rebuild mode. Beyond his 12-2 record and 2.25 ERA, the 22-year-old allowed just 97 hits over 124 innings with 144 strikeouts.

OF Jose Azocar (21st): The athletic 21-year-old Venezuelan had an impressive 2016 season at Class A West Michigan before struggling at Class A Advanced Lakeland, including a 122-to-14 strikeout-to-walk ratio.
SS Sergio Alcantara (24th): Some believe the slick-fielding 21-year-old, acquired from Arizona in the J.D. Martinez trade, could field his position in the big leagues right now despite not playing above Class A ball. How much he'll hit is the question, both now and long term.
RHP Gerson Moreno (25th): The hard-throwing reliever dominated Florida State League pitching at with Lakeland before advancing to Erie, combining 66 strikeouts over 50 1/3 innings between the two stops. Not finished, he has continued the trend with a strong Arizona Fall League campaign. He's the latest potential late-innings reliever coming up through the Tigers' system, and the type of arm teams like to stash in their bullpen for a year.
RHP Adam Ravenelle (26th): The former Vanderbilt closer had a rough, injury-delayed season after spending Spring Training as a non-roster invite in big league camp. Still, with a good fastball and 82 innings at Double-A over the past two seasons, he's potentially close to the Majors if he can stay healthy and hone his slider.
RHP Spencer Turnbull (28th): The former second-round pick out of Alabama has battled injuries, but posted a 7-3 record and 3.05 ERA in 15 starts at Lakeland to earn a late-season stint in Erie. He then went back to the Arizona Fall League and has strung together solid outings following a rough debut. The Tigers still see him as a starter, but some believe he has the arsenal and arm strength to convert to relief.
Among the unranked prospects who could garner roster consideration:
RHP Paul Voelker: The hard-throwing reliever missed 50 games due to suspension but struck out 40 batters over 36 innings with a 2.00 ERA across three levels, ending at Triple-A Toledo. The 25-year-old has a chance to compete for a spot in Detroit's bullpen at some point next year along with many other young arms, making him a strong candidate to protect.
C Grayson Greiner: The Tigers have some catching depth in their system with Jake Rogers coming over from the Astros in the Justin Verlander trade, but they like the potential of the 6-foot-6 Greiner, whose defensive skills behind the plate belie his body frame. He could be in position to serve as catching insurance for the Tigers if James McCann or John Hicks spend time on the disabled list next season.
IF Kody Eaves: The second/third baseman has distinguished himself with a strong Arizona Fall League campaign after shuttling between Erie and Toledo over the summer.