Opening Day assignments are always a good reminder of a maxim common among coaches and front office personnel: player development is not linear.
No matter how closely you follow Minor League Baseball and think you have a hold on exactly where certain players will be on the first day of the season, you should always leave room for surprises. Some players may get pushed a little harder, perhaps skipping levels altogether. Others might be revisiting the same level or get held back a little as compared to their peers. Each system has its own philosophy on how aggressively it can (or cannot) move its most talented youngsters, which becomes crystal clear on the first day of the Minor League season.
With that in mind, these are the 2019 regular season's most and least aggressive opening assignments for players on MLB.com's Top 100 Prospects list.

Most aggressive

Forrest Whitley, Astros RHP, Triple-A Round Rock: Gauging by skill alone, this may not be an aggressive assignment. Whitley is the top pitching prospect in baseball, with four plus offerings -- including a plus-plus fastball. Many expect him to be in Houston at some point this season, and he'll slot quite nicely into that rotation next to Justin Verlander and Gerrit Cole. There is a clear logic to putting him one step away for Opening Night. However, Whitley has a total of 26 1/3 innings of Double-A experience on his resume. His 2018 season was mostly wiped out by a 50-game drug suspension and various oblique and lat injuries. He made up for some of the lost time in the Arizona Fall League, but few would have questioned the Astros' judgment had they shipped Whitley back to Corpus Christi for a little more seasoning. Instead, their decision to send him to Triple-A immediately speaks volumes about a) their desire to challenge his stuff out of the gate and b) their confidence that he can rise to that challenge. If Whitley aces the test of the offense-oriented Pacific Coast League, he could blast off to Houston at some point in the first half.
Drew Waters, Braves OF, Double-A Mississippi: The Braves have a pair of talented center fielders in Waters and No. 35 overall prospect Cristian Pache. Both will roam the grass in the Southern League to begin the season. Wait, what? The assignment makes sense for Pache, who played 29 games with Mississippi at the end of last year. Waters, however, got about the same amount of playing time at Class A Advanced Florida and yet he's still moving up a level. This isn't to say the 2017 second-rounder can't handle the jump. The 20-year-old switch-hitter has speed to burn and showed a solid bat with a .293/.343/.476 line in his first full season in 2018. However, his best skills are on the defensive side, where his glove and arm rate out as plus. Pache is still the better center fielder -- he's widely considered the best in the Minors -- so it's likely Waters will be moving to a corner in most M-Braves games. But Atlanta's willingness to pair the two this early could indicate how much they factor, alongside the newly extended Ronald Acuña Jr., into the organization's long-term plans. In the meantime, there may not be many fly balls touching the grass in Mississippi.
Luis Garcia, Nationals INF, Double-A Harrisburg: When the Nationals really like a young player, they show it. They carried on that tradition with players like Victor Robles and Juan Soto, and they continue it by moving the 18-year-old Garcia to the Minors' second-highest level already. With Garcia's birthday coming in May, this will technically be his age-19 season. Only four batters got any significant amount of playing time in the Eastern League during their age-19 seasons in 2018, and they form quite the list -- Vladimir Guerrero Jr., Soto, Andrés Giménez and Isaac Paredes. Batting from the left side, Garcia hit .298/.336/.406 in 127 games between Class A Hagerstown and Class A Advanced Potomac last season. Only 49 of those games came at the latter, however, so he could have moved back to the Carolina League. Instead, Washington keeps pushing him, and he took advantage of a taste of Major League camp to go 6-for-19 (.316) in 15 games this spring. His defensive remains up in the air -- Garcia has mostly played shortstop but has covered second and third in the past as well -- but if he can hit as well at Harrisburg as he has everywhere else, the Nats will find a spot for him, as they did last season with Soto.
Jazz Chisholm, D-backs SS, Double-A Jackson: Chisholm's arrow was certainly pointing up coming into the spring. The 21-year-old, left-handed-hitting shortstop became Arizona's top prospect after he broke out with a .272/.329/.513 line, 25 homers and 17 steals between Class A Kane County and Class A Advanced Visalia last year. The Bahamas native had battled the health bug earlier in his career -- namely a torn right meniscus in 2017 -- but he's more than back on track now. In fact, Chisholm played 36 games last season in Visalia and went deep 10 times over that span. Perhaps the D-backs know there's little for him to learn by continuing to swat in the hitter-friendly environment of the California League, and that led the organization to push the No. 59 overall prospect to the Southern League this quickly. Whatever the reasoning, this will be the biggest test of Chisholm's young career. Should he pass it, he could be one of the game's most exciting prospects by the end of the season.
Nico Hoerner, Cubs SS, Double-A Tennessee: There were 30 players selected in the first round of the 2018 Draft. Thirteen of them were picked from four-year colleges. Only one of those 13 is opening the 2019 season at Double-A, and it's not Casey Mize, Joey Bart or Nick Madrigal. Obviously, it's Hoerner, the 24th overall selection in that Draft. The bump to the Southern League comes partly on the strength of his AFL campaign. The Cubs sent the Stanford product to three different levels during the 2018 season before he suffered a left elbow injury in mid-July while with Class A South Bend. They let him make up for those lost at-bats in the Fall League, and Hoerner responded by hitting .337/.362/.506 with nine extra-base hits in 21 games as the only AFL position player from the 2018 Draft. Chicago noted at the time that the last Draft pick they'd sent that quickly to the Fall League was Kris Bryant, who opened the following season at Tennessee. Hoerner -- an impressive all-around hitter with above-average speed -- doesn't have Bryant's ceiling, but his quick ascent shows how much he's impressed the Cubs in a short time.

Least aggressive

Alec Bohm, Phillies 3B, Class A Lakewood: Of the aforementioned 13 first-rounders out of college last year, three are opening in Class A. The two besides Bohm -- Logan Gilbert and Ryan Rolison -- aren't Top-100 prospects, and they certainly weren't the No. 3 overall pick like the Phillies third baseman. Bohm (No. 58 overall) did have a rough go of his first crack at pro ball last summer, hitting .224/.314/.290 with no homers in 29 games with Class A Short Season Williamsport. However, post-Draft seasons should always be taken with a grain of salt; the player in question is coming off a college or high school campaign and adjusting to pro ball on and off the field. Also, Bohm's 2018 season included some time on the injured list with a hurt shin from a hit-by-pitch. When he's on, Bohm is an above-average hitter with good power. He showed that in his junior year with Wichita State, batting .339/.436/.625 with 16 homers in 57 games. He's good enough to handle the rigors of Class A Advanced right now, given his age and experience, but the Phillies might be sending him to the South Atlantic League to build his confidence at the start of his first full season. As a result, don't make too much of a hot start for Bohm in Lakewood.
Yusniel Díaz, Orioles OF, Double-A Bowie: Diaz was acquired from the Dodgers in the Manny Machado deal at last year's Trade Deadline and quickly became the crown jewel in Baltimore's rebuilding efforts. He played 59 games at Tulsa and 38 with Bowie, for a total of 97 games with Double-A affiliates in 2018. Yet the 22-year-old is back at the same level to open this season. It's true that Diaz hit a bit of a wall after the trade, with a .239/.329/.403 line and 11 extra-base hits, but he was still an above-average hitter by Eastern League standards, putting up a 106 wRC+ in that span. With all five of his tools grading as at least average, he could have handled a move to Triple-A Norfolk with a spot in a wide-open Baltimore outfield not far beyond. It still may be within Diaz's reach this summer, but it'll take two stops -- not one -- for the native of Cuba to reach The Show.
Royce Lewis, Twins SS, Class A Advanced Fort Myers: These last two are picking nits, for sure, but that's the point of this column. MLB.com's No. 5 overall prospect was moved up to Fort Myers from Class A Cedar Rapids on July 14 last season, and he hit .255/.327/.399 with five homers and six steals in 46 games during the regular season, then left the yard three times in six postseason games to help the Miracle capture a Florida State League title. There's some room for growth there, but no one would have batted an eye at Lewis getting his first look at Double-A. Alex Kirilloff, with whom Lewis was paired for most of 2018, is scheduled to start at Pensacola when he returns from a slight wrist injury. Keeping those Twins together would have provided another exciting look at Minnesota's future. That's still likely to come at some point in the first half, but it's not this point.
Luis Urías, Padres INF, Triple-A El Paso: This offseason, the running story was that Urias would be the Padres' Opening Day shortstop and move over to second base when Fernando Tatis Jr. eventually came up after playing in Triple-A El Paso. That script got flipped when San Diego announced it was adding Tatis to the Major League roster and optioning Urias to the Pacific Coast League. It's true that Urias didn't exactly push the envelope with his Cactus League play (.224/.309/.429, 16 strikeouts in 19 games). But he didn't have much left to prove in Triple-A after ranking seventh in the PCL with a .398 OBP as a 21-year-old last season. There's a world in which the Padres infield is a mix of promising youngsters in Urias and Tatis next to established veterans Machado and Eric Hosmer, and that world isn't far off. But the free-agent signing of Ian Kinsler complicated matters a bit, and that means Urias will have to continue to show a plus hit tool with the Chihuahuas before assuming his long-term spot at second in San Diego.