I scanned the Mariners RISP (Runner in Scoring Position batting average) for each of the first 140 games that they played. Going back and forth from box score to box score online can be tedious and I might have an error or two. Baseball-Reference.com shows the Mariners with 244 hits in 1,067 at bats with RISP for a .229 average through the first 140 games. I somehow added 4 additional at bats, so I had them with 244 hits in 1,071 at bats for a .228 average. It would be nice to be spot on, but I am going to call it good.
Running with my stats, in 74 of the games (52.9%), the Mariners hit .200 or less with runners in scoring position. In fact, in those games they were 52-535 for a .097 average. If my four extra at bats are among those games, then they really hit .098. In an additional ten games they were 1-3 or 1-4, better than .200 but the bigger story was that they only had three or four in scoring position during those games. Those 74 + 10 games represent 60% of the first 140 games.
In the remaining 56 games (40% of 140), the Mariners hit better than .200 with RISP and had two or more hits (no 1-3 or 1-4 RISP games). In fact, they went 192-536 in those 56 games for a .358 average. Pretty good. Gives them a really good shot of winning those games unless their pitching got blown out.
Among the 74+10 games in which the Mariners had some hitting problems, clearly they won some of the games because you can score runs without a runner in scoring position...the solo home run, for example...or you can win a pitching duel. But I would venture to say that an .097 or .098 average with RISP would be tough to overcome. Right now, to be in a wild card spot, you have to have won over 55% of your games (Tampa has the worst record for holding a wild card with .554 Win%). If the goal is simply to win more than half your games, you have to win more than 50% obviously. If you hit under .100 with RISP in almost 53% of the games and only have three or four runners in scoring position in an additional ten games, chances of just getting to .500 Win% for the season are pretty slim. Getting to the playoffs would be even slimmer.
There is no novelty in pointing out that Mariner bats have struggled. And it would be great to not only point to a fault, but also to present a solution. I don't have one unfortunately. Get/develop clutch hitters? I have read that there is really no such thing as a clutch hitter, that it all evens out over larger sample sizes, that someone with good average in the clutch also has a good average anyway, and visa versa (the Ms are only hitting .241...not too far removed from .229 average with RISP). I am sure that others would debate that. Perhaps the stats that I dug up are more an issue of consistency in hitting. If you score 100 runs in one game and no runs in nine games, even though you average ten runs a game, you probably have a record of 1-9. This stat (RISP avg) is only one of the elements that determine the outcome of a game, and heck, maybe someone can show that it really isn't that important. Nonetheless, I felt that someone might find the data that I dug up to be interesting, so there you go.