Before Wednesday's game, the Washington Nationals officially promoted left-handed pitcher Jackson Kent to the major league roster.It was reported that this move was going to happen, and veteran right-hander Miles Mikolas was eventually designated for assignment to make way for Kent's MLB debut. While there was some palpable excitement about what Kent could do, it wasn't known how the 23-year-old would perform after he started this season at the Double-A level.Well, Kent certainly flashed his upside, but he also showed some of his flaws, too. In the first inning, after he struck out the first batter he faced before he walked the next two. He then struck out the following two batters to get out of the frame unscathed. Kent didn't allow his first hit until the top of the fourth inning, but he ran into trouble in the fifth when he gave up a leadoff single, a walk and then an RBI double to NL MVP frontrunner Pete Crow-Armstrong that caused manager Blake Butera to pull the lefty from his debut.Ultimately, Kent's final line was three earned runs on three hits with five walks and six strikeouts across four innings pitched. However, despite things going off the rails a bit at the end, there was a lot to like about what the young lefty accomplished.Passed the Eye TestFirst, when just glancing at Kent on the mound, he looked the part of a big league starting pitcher to me. While he's not towering at 6-foot-3, he has a presence to him. He also operated like a seasoned veteran during his debut, as he was able to get out of jams that he created for himself.At the age of 23, facing a Chicago Cubs lineup that has the best OPS in the majors against left-handed pitchers, it would have been easy for Kent to get overwhelmed. But that largely didn't happen, and that bodes well for him sticking in Washington's rotation for the long haul.Didn't Have High VelocityI would classify Kent's debut as a successful one. Despite the three earned runs he allowed in the fifth inning and the high number of walks that were issued, it was impressive to see him navigate this potent Cubs lineup in the way he did.What stood out was the lack of velocity he had while doing so. Kent was able to climb up the Nationals' pipeline quickly this season because he threw his fastball harder than he had in the past. But he only threw six pitches harder than 94 mph on Wednesday, and he only was above 95 mph once. All of those came in the first inning, and by the time he reached the fifth, his heater was solely in the low-90 mph range.That could be glass-half-full or glass-half-empty depending on how you look at it. But I actually think this was a good sign that Kent can be an impactful starting pitcher in the majors even if his fastball doesn't routinely have the upper-end velocity that it possesses.Lack of Command at TimesWith five walks on the night, it was hard for Kent's lack of command to not stand out. That could be chalked up to nerves. After all, it was his MLB debut in front of home fans against a team that has championship aspirations with multiple All-Stars throughout the lineup. Because of that, I'm going to cut him a lot of slack when it comes to the walks he issued.However, what really stood out was the number of times he had a four-pitch walk, as three out of his five fell into that category. Was that a result of getting behind and being cautious so he didn't make a lethal mistake to one of these elite hitters, or is this a sign of things to come?We'll find out over the course of his next few starts. But it should be pointed out that he wasn't a high-walk guy with Rochester, as he issued a base on balls just 8.2% of the time.Showed Off Strikeout StuffKent wasn't considered to have big-time strikeout stuff coming up the pipeline. Across 44 starts in the minors, he had 237 K's over 217 1/3 innings pitched. But on Wednesday, the lefty was able to show off his ability to ring up batters, and he did so against a formidable opponent.Coming into the game, Chicago was the best overall offense in terms of wRC+ (112). They were tied for No. 16 in the majors with a 21.7% strikeout rate. Against left-handers, they have been even better in wRC+ (124) while keeping the same exact K rate, which shows how dangerous of a challenge this lineup was for Kent.He was able to navigate things well, though. Three of his six strikeouts came in the first inning, with two more coming in the third and his final one taking place in the fourth. Based on the success the Cubs have had against lefties this season, seeing Kent wring up six of their batters was a good sign of what could be coming for the 23-year-old in the future.Add us as a preferred source on GoogleFollow