Prospect rankings typically emphasize a player’s ceiling. Yet a case can be made that prospects with well-defined floors are far more valuable.
Enter Brian Johnson. The lefthander has the most advanced feel for pitching of anyone in the Red Sox farm system, an ability to carve the strike zone with four pitches – fastball, curve, change, slider – but without a true wow factor on any of them. He typically pitches to contact, generating swings and misses opportunistically rather than in volume.
Yet Johnson looks like a pitcher who is ready to contribute at the big league level, someone capable of executing a gameplan thanks to command of a diverse arsenal that is not typically seen in Triple A prospects. The latest evidence of the notion came on Tuesday, in an 89-minute, complete-game, seven-inning shutout on the front end of a doubleheader.
Johnson permitted just two hits (both singles), walking one, and striking out five. He threw 58 of 90 pitches (64 percent) for strikes while getting six swings and misses. He’s now permitted two or fewer earned runs in 24 of his last 25 regular season starts dating just over a full calendar year to last April 18, when he was still in High A Salem. He has a mind-blowing 1.46 ERA during that time. In three games this year, he is 2-1 with a 0.56 ERA, a .175 opponents’ batting average, 18 strikeouts, and four walks in 16 innings.
Most evaluators view Johnson as a near-lock to be a big league starter, but with the ceiling of a back-of-the-rotation (No. 4 or No. 5) starter. As such, he’s behind fellow lefties and PawSox teammates Henry Owens and Eduardo Rodriguez in prospect rankings given their swing-and-miss potential.
But prospect rankings represent snapshots of perceived potential rather than exercises in certainty. And as Johnson has churned relentlessly through outing after outing, he’s arrived at a point where few if any evaluators would be surprised if he has the best big league career of any pitcher currently in the Red Sox system.
TRIPLE A PAWTUCKET RED SOX: 1-0 WIN, 3-1 LOSS VS. BUFFALO
■ Corner infielder Travis Shaw collected three of the PawSox’ six hits and both of the team’s extra-base hits in the doubleheader, going 3-for-6 with two doubles. The 25-year-old played one game at first and one at third.
■ Shortstop Deven Marrero had a rough day, going 0-for-5 with four strikeouts and his second error of the season. In the process, his average dropped to .273 (with a .368 OBP and .455 slugging mark), its lowest point since his second game of the season.
■ Though Jackie Bradley Jr. went 0-for-6 with a pair of strikeouts in the doubleheader, he did contribute to the PawSox victory with an outfield assist.
DOUBLE A PORTLAND SEA DOGS: 4-0 LOSS, 8-1 WIN AT NEW BRITAIN
■ Utility man Carlos Asuaje went 3-for-3 with a double and a walk in the second game after going 0-for-2 with a walk in the first contest. The player who led the Red Sox system in OPS last year is off to a slower start this year, hitting .243 but with a .364 OBP and .351 slugging mark in Portland.
■ Lefthander Robby Scott, typically a reliever, delivered an impressive spot start, tossing four shutout innings in which he permitted three hits, walked none, and struck out four.
HIGH A SALEM RED SOX: 7-4 LOSS VS. MYRTLE BEACH
■ Outfielder Manuel Margot continued his outrageous season-opening run, going 2-for-4 with a double and, for the 10th straight game, not striking out. He was caught stealing for the first time this year. Still, Margot has an eye-catching .375/.381/.650 line to open the year.
■ First baseman Sam Travis had his second multi-hit game of the year, going 2-for-5 with a triple and also stealing a bag. Travis has stumbled out of the gate, hitting .175/.344/.325, though he’s fared well early against lefties, forging a .375/.444/.500 line against southpaws.
SINGLE A GREENVILLE DRIVE: 5-3 WIN AT LEXINGTON
■ Reports from Red Sox officials about Ty Buttrey so far this year have been consistent. The righthander has been better than anyone has seen at any other point in his professional career. The 2012 fourth-rounder allowed three runs (two earned) in a career-high seven innings, permitting six hits, walking one, and striking out three. He recorded 11 outs via groundball. The 22-year-old is working with a low- to mid-90s fastball and power curve that is putting him back on the prospect map.
■ Mario Alcantara appears to be taking well to fulltime life in the bullpen. He recorded two scoreless innings in which he allowed one hit and punched out three for his first save. The 22-year-old has posted 6 2/3 scoreless innings with seven strikeouts and no walks so far, a marked contrast to the strike-throwing difficulties the righthander has experienced in the past.
■ Mauricio Dubon keeps hitting. He went 2-for-4 for his fifth multi-hit game of the year. The 20-year-old now has a .364/.391/.455 line.
Alex Speier can be reached at alex.speier@globe.com. Follow him on twitter at @alexspeier.