We thought we knew.
Jose Cabrera and Carlos Gonzalez were surefire studs, Manny Machado and Francisco Lindor were on their way up and Justin Smoak was destined to spend the season on waivers in mixed leagues.
Nearly four months later, we have been reminded that the unpredictable nature of fantasy baseball remains one of the biggest draws to playing this great game. And with slightly more than two months to play, player values will continue to spike and lag. But among the more than 750 Major Leaguers, the following 10 men rank as the most fascinating to follow down the stretch.
Salvador Perez, catcher, Royals
While Gary Sanchez  and Buster Posey  dominate the discussion at the catcher position, Perez has used his typically heavy workload and increased power skills to rank as the most productive backstop to this point in the season. In fact, owners who notice his outstanding rate of fly balls (49.2 percent) and hard contact (40.3 percent) should have little concern that Perez can maintain his current 30-homer and 100-RBI pace. But with a lifetime .700 OPS in the second half compared to a .784 mark prior to the All-Star break, the backstop will need to prove that he can avoid the late-season fade that has become his career norm.
Down-the-stretch prediction: Perez reverses his career trend and continues to excel down the stretch.

Miguel Cabrera, first baseman, Tigers
Cabrera has been a major disappointment, logging career-worst marks in batting average (.262) and OPS (.784). And his performance dip could not have come at a worse time, as the first-base position has been ripe with surging sluggers such as Justin Smoak, Logan Morrison , Eric Thames  and Justin Bour . As surprising as this may seem, Cabrera will need to find his stroke in the coming weeks to avoid being relegated to some shallow-league benches in September.
Down-the-stretch prediction: Cabrera struggles to get on track and is not selected during the initial five rounds of many 2018 drafts.
Justin Smoak, first baseman, Blue Jays
Smoak is arguably the most intriguing member of the first-base surprises, as the lifetime .232 hitter is on pace to hit .298 with more than 40 home runs. And with a reasonable HR/FB rate (22.4 percent) and BABIP (.310), the slugger has been fueling his success with skills rather than good fortune. With a strong finish to the season, Smoak could rank as this year's biggest breakout performer and spark many fantasy titles.
Down-the-stretch prediction: Smoak finishes the season with a .280 average and 40 home runs.

Manny Machado, 3B/SS, Orioles
Hitting .237 and on pace to compile fewer than 85 RBIs and 75 runs scored, Machado has provided the most disappointing returns among those who were selected in the first round of shallow-league drafts. But the news is not all bad, as the 25-year-old has produced a .910 OPS this month and is on pace to tally more than 30 homers. Also, his penchant for hard contact (92.1 mph average exit velocity) makes him a prime candidate to reward patient owners down the stretch.
Down-the-stretch prediction: Machado gets back on track, but not to the degree that puts him in the first round of 2018 drafts.
Francisco Lindor, shortstop, Indians
Despite being on pace for roughly 90 runs scored and 25 home runs, Lindor has been a disappointing early-round pick with a .257 average and four stolen bases. The shortstop had some early-season success with a newfound fly-ball-heavy approach (12 homers in April and May), but the altered batted-ball profile has seemingly contributed to a lowly .266 BABIP and he has logged just two long balls and one swipe since June 1.  
Down-the-stretch prediction: Lindor continues to disappoint and ranks among the biggest boom-or-bust options for next year.
Carlos Gonzalez, outfielder, Rockies
An early-round pick in most mixed-league drafts, Gonzalez has performed at a level (.218/.296/.335 slash line) that has pushed him to waivers in some leagues. If the 31-year-old can get on track, he could provide significant value with the benefit of his hitter-friendly home park and productive supporting cast. But further struggles could cause CarGo to lose playing time in a crowded Rockies outfield.
Down-the-stretch prediction: Gonzalez will not improve to the point where mixed-league owners regret releasing him to waivers.

Masahiro Tanaka, starter, Yankees
After logging a 6.34 ERA across his initial 14 starts, Tanaka has shown signs of a rebound by posting a 3.00 ERA and a 1.03 WHIP across his past five outings. Still, owners will need to tread carefully with a starter who calls home to a hitter-friendly venue and owns a 2.0 HR/9 rate this year. With ace-level starters in short supply, those who own Tanaka could see their title hopes rest on his ability to find his top form down the stretch.
Down-the-stretch prediction: Tanaka does a better job keeping the ball in the yard and posts a 3.50 ERA in the second half.
Madison Bumgarner, starter, Giants
Limited to just four starts, Bumgarner lost more time to injury in the first half than any other early-round pick. And while he was arguably the most reliable ace in baseball across the previous six seasons, the southpaw now needs to prove that he has completely recovered from the off-field shoulder injury he sustained in April. Time is quickly dwindling for Bumgarner -- who has yet to win a game this year -- to provide a stretch of ace-level production for his patient owners.
Down-the-stretch prediction: A combination of poor individual performance and lack of run support keeps Bumgarner outside the top-20 second-half starters.
Dallas Keuchel, starter, Astros
Keuchel has been an elite arm on a per-start basis, going 9-0 with a 1.67 ERA and a 0.87 WHIP across 11 starts. But owners of the left-hander will head into the stretch run worrying about both his ability to move past persistent neck woes and avoid regression towards the 4.55 ERA he logged during an injury-impacted 2016 campaign.
Down-the-stretch prediction: Keuchel returns in late July, avoids further injury issues and leads many teams to fantasy titles.
Rich Hill, starter, Dodgers
A well-known injury risk, Hill threw just eight innings prior to May 16. And the southpaw was surprisingly ineffective after returning to the rotation, posting a 5.67 ERA and a 1.59 WHIP across six starts from May 16 to June 15 before finding his form and logging a 1.74 ERA and a 0.81 WHIP across his past five outings. By avoiding additional DL stints, Hill could reward owners who remained patient through his injuries and ineffective stretches.
Down-the-stretch prediction: Hill stays off the disabled list and ranks among the top-20 starters from this point forward.