My hands are sweating. My mouth is dry. My face is white. Tre Mason just received another first-quarter carry, revealing that he is the new starting running back for the St. Louis Rams, and I own him in ZERO fantasy leagues.

Last Sunday night, and late into Monday morning, I stared at the ceiling, unable to understand how I missed an ascending running back of Tre Mason‘s caliber. Mason checks all of the boxes that typically drive a fantasy ascent:

1. Opportunity. The Rams coaching staff is gaining trust, exemplified by Tre Mason’s skyrocketing snap share. His snaps have risen from 0 to 9 to 27 in a three-week span.

2. Supporting Cast. The Rams have a top-5 offensive line. According to Football Outsiders, the Rams’ offensive line has allowed opposing defenses to stuff running backs on only 10-percent of carries, the lowest percentage in the NFL.

3. On-field productivity. Despite playing in the SEC in 2013, Tre Mason posted a 31.7% Dominator Rating (65th percentile), which measures a running back’s contribution to total team offensive production. Even more impressive, Mason was only 19-years-old when the Tigers anointed him their starting tail back.

4. Raw athleticism: Tre Mason’s workout metrics on PlayerProfiler support the explosive speed and lateral quickness that the naked eye beheld last Sunday:

40-time: 4.50 (70th percentile)

Burst Score: 128.5 (88th percentile)

Agility Score: 10.85 (94th percentile)

Mason’s phenomenal college resume and workout metrics propelled his draft stock upward last April, and the Rams surprisingly selected him in the third round. The pick was particularly shocking after the team had seemingly just struck gold with 6th round rookie, Zac Stacy, a year earlier.

Zac Stacy carried many fantasy owners to league championships in 2013. Fantasy gamers were also impressed by Stacy’s 106.7 (95th percentile) Athleticism Score on PlayerProfiler, which is propped up to his 32.8 BMI, 10.87 Agility Score, and 27 Bench Reps. That combination of strength and agility is what allowed him to seize the Rams’ starting running back job last season, but his 3.9 average yards per carry in both 2013 and 2014 were ominous.

The Tre Mason draft pick was a harbinger that St. Louis viewed Stacy as a bridge back, not a franchise player. The Rams wanted a faster, burstier back capable of scoring on any given play, and got exactly that with Tre Mason. The Rams’ starting running back job is now his to lose.

How did I, Mr. Late Round Everything, miss this juicy opportunity? Staring at the ceiling at 3 AM, it finally hit me… my Tre Mason blind spot had a name: Benny Cunningham. My fantasy crush on Cunningham started upon seeing him destroy Georgia Tech to the tune of 217 yards and five touchdowns playing for Middle Tennessee State in 2012. With the Rams, Cunningham has continued to impress, demonstrating an ultra-low pad level, short-area burst, and fluid receiving skills.

Throughout the season, I had been laser-focused on Benny Cunningham‘s increased touches, while ignoring the better back lurking at the No. 3 position on the Rams’ depth chart, poised to jump the line and steal Zac Stacy’s job before my boy Benny could make a move. That’s bursty.

While Tre Mason is the running back to own in St. Louis this season, a few flaws will prevent his ascent to fantasy RB1 status and offer hope to Cunningham’s fantasy owners. Mason is a poor receiver, who caught only 12 passes during his final year at Auburn, and he is an even worse pass blocker. He has also shown a Lamar Millerian tendency to run to contact in the second level. In spite of these flaws, Mason will be well-positioned to produce RB2-level fantasy numbers this season while getting 10-20 carries, depending on game flow, behind the Rams’ offensive line. Mason’s passing down limitations and poor field vision will also allow Benny Cunningham to retain flex-appeal operating primarily on the goal line, in passing situations, and in the hurry-up offense.

Upon realizing that my affinity for Benny Cunningham had blinded me to Tre Mason’s pending ascent, I quickly drifted off to sleep. As the sun rose on Monday morning, I bolted upright with a prescient thought: get Charles Sims.

The situation in Tampa Bay is strikingly similar to St. Louis. Doug Martin‘s athletic profile and on-field inefficiency mirror Zac Stacy’s, and Bobby Rainey, like Benny Cunningham, is an agile back with a low center of gravity who is best deployed in short yardage and passing down situations.

Stashed on the Buccaneer’s injured reserve and expected to return in week 10, Charles Sims is a less bursty, more versatile version of Tre Mason. At West Virginia, Sims was highly productive. He posted a 35.8% Dominator Rating (76th percentile), and like Tre Mason, Sims was only 19-years-old when first anointed him a starting tail back (then with the University of Houston).

Charles Sims’ raw athleticism also compares favorably to Tre Mason. In fact, Buccaneer scouts and coaches were enamored enough to draft Sims ahead of Tre Mason in the third round (pick 3.05). Furthermore, Sims’ workout metrics on PlayerProfiler demonstrate superior speed and burst to Martin and Rainey:

40-time: 4.48 (77th percentile)

Burst Score: 126.5 (86th percentile)

Agility Score: 11.46 (29th percentile)

While Charles Sims’ Burst Score and Agility Score are lower than Tre Mason’s, Sims is a better all-around football player. His 45 receptions for 401 yards at West Virginia in 2013 indicate that he is better equipped than Mason to slide into an every-down role at this point in their respective careers. After my premonition, I began stashing Sims in all leagues where I am projected to make the playoffs.

I have tremendous respect for Bobby Rainey and Benny Cunningham. Both were undrafted out of non-BCS conference schools and proceeded to overcome long odds to quickly become key NFL contributors. Sentimental attachment to small school underdogs, however, doesn’t win fantasy championships.

Tre Mason is so two days ago. Today is a new day. Get Charles Sims.

Matt Kelley (@fantasy_mansion) is an XN Sports contributor and founder of RotoUnderworld (@rotounderworld) and PlayerProfiler.com, which distills a wide range of advanced metrics into a single player snapshot.