HOUSTON — Kai-Wei Teng is a symptom of more substantial issues, some of them self-inflicted and others just a part of this star-crossed Houston Astros season. On a full-strength pitching staff, Teng should be a swingman, someone available for multi-inning stints to shield relievers from overuse.The next day this Astros staff feels complete will be the first, so on Monday night, Teng started a meaningful game. He commanded nothing, displayed diminished fastball velocity and, after three innings, had already ceded five runs to the Detroit Tigers.Teng still emerged for the fourth, with left-hander Steven Okert starting to throw in Houston’s bullpen, suggesting that manager Joe Espada at least contemplated an alternative at that point in an eventual 9-3 loss.No straightforward choice existed, but such is life for any major-league manager. Heightened scrutiny follows one in the final year of their contract, a fact Espada has embraced since his tenure-defining season began.Espada has acted as such. He has written 74 different batting orders in the season’s first 74 games and sent a slew of pinch hitters to create late-game platoon advantages. His bullpen management has grown more aggressive, but not at the expense of his relievers’ well-being.Trying to squeeze three more outs from Teng on Monday night underscored it. Teng only collected one, forcing Espada to summon Okert. He struck out two batters on eight pitches and kept Houston’s deficit at two runs.Five offensive innings remained and Espada needed to keep the game within reach. Deploying one of his most dependable relievers is the best way to do so. Okert delivered, but that obscured a larger point.Those eight pitches were all Okert could provide. Three days earlier, Okert collected a season-high seven outs across a 28-pitch appearance he should not have made. Tatsuya Imai, the team’s embattled, $18 million enigma, did not finish the first inning after being staked to a nine-run lead before throwing a pitch.Houston still won that game against the Kansas City Royals, but braced for the implications of Imai’s implosion. The team used six relievers, three of whom threw at least 27 pitches. Doing that in any game is grounds for concern.