The Double-A Mississippi right-hander worked six scoreless innings in the Braves' 6-0 shutout of Montgomery on Monday, scattering just three hits and a walk while striking out four.
It was his fourth straight start with at least four strikeouts, after fanning more than three just once in his previous seven starts to begin the season, on Opening Day. In all four outings, he's gone at least six innings while limiting his opponents to three earned runs or fewer.
"Being able to throw my pitches for strikes [has helped]," Spruill said of his improving ability to get batters to swing and miss. "All three of my pitches have been working as out pitches for me, and being able to do that is definitely leading to fewer hits and fewer runs each game."
In just those four outings, Spruill (5-4) has seen his ERA fall over a run, from 4.58, where it stood after his May 6 outing against Pensacola, to 3.50, where it landed after his clean effort against Montgomery on Monday.
In that stretch he's worked as many as eight innings in a May 11 win over Huntsville, and struck out as many as seven batters, as he did May 23 against Pensacola. Spruill said better control of his three primary pitches -- a two-seam fastball, a splitter and a slider -- has allowed him to strike out batters more easily.
His last four games have put his strikeout totals back in line with his historical norms. Between Class A Advanced Lynchburg and Mississippi last season, Atlanta's No. 7 prospect posted 5.56 strikeouts-per-nine innings mark in 27 starts. That led to a 3.19 ERA in 174 2/3 innings across the two levels.
After his first six outings this season, however, he was at just 3.34 strikeouts-per-nine innings. The 2008 second-round Draft pick's past four starts have brought that number back up to 5.60, nearly identical to what it was in 2011.
The Virginia native has also managed to keep his walks down, issuing just three free passes in the 27 innings that have spanned those four starts.
On Monday, Mississippi relievers Chris Jones and Billy Bullock came in to pitch three hitless innings and preserve the shutout for Spruill. Jones walked one and struck out one in two frames, while Bullock posted the same line in one inning of work.
Spruill praised the Mississippi bullpen, saying he thought it matches up favorably with any other in the Southern League.
"I think we have one of the best bullpens in the league," he said. "There's very few times where the starter comes out with a lead and the bullpen gives it up. Every single guy out there could be a closer on this team. Unfortunately, you can only have one."
Cory Harrilchak and Barrett Kleinknecht led the Mississippi offense Monday, with each hitter providing two RBIs.
"I think our team played great baseball," said Spruill. "Great defense, they hit the ball well and we only gave up three hits in nine innings of work, so we pitched well too."