In poker, a semi-bluff is a moderately risky strategy that can pay big, with limited downside. Assume you have a hand midway through that could win, but probably won't. However, if the next card shows properly, you could have a much better hand, that should win. The semi-bluff represents a better hand than you have, trying to scare off your opponent... If he returns with a bigger raise, you fold and he wins a few extra chips. You might end up scaring him off, hitting your card, or winning in a showdown. If played properly and rarely, a semi-bluff can be a useful tool.
In the spring, when the Cubs signed Donnie Murphy, there was no fanfare. He was sent to Triple-A Iowa, and hit in the middle of the order, playing mostly shortstop. When he was called up in early August, nothing was expected of him. And the less of that nothing, the better. In his seven previous big league campaigns, he had had two seasons with an OPS+ of higher than 76 (which he posted last season). One of those had been in a campaign with under 50 at-bats.
Naturally, he's hit very well since his recall. His 133 plate appearances makes this his busiest season ever. His 10 homers eclipsed a career high of six, and his next RBI ties his career best. Cody Ransom is among his top career comps, but Terry Shumpert appears as well. Is Murphy a semi-bluff candidate?
The two main options for the Cubs after the season are to let him go, or offer him arbitration. (Yowzers, that seems odd, with as long as he's been around.) It could be that he has figured 'it' out later in his career (he turns 31 in March). Or, he could be merely playing out of his skull, and will go Cody Ransom in a matter of days. Nonetheless, it would probably be helpful to properly assess his future career track.
I don't imagine he would cost much in arbitration. If the team likes him as a backup/platoon guy, there are probably worse options, and it's doubtful Murphy would drive too hard of a bargain. That said, if released/non-tendered, he could possibly get a (dare I even say it) a major league contract in the off-season. Teams are always looking for quality middle infield reserves.
Of course, there are ways around things. He could be signed (perhaps on the cheap), then designated for assignment later, hoping to get him to come back on a deal that might be more than he would make elsewhere. This would be the Blake DeWitt plan.
In reality, though, it seems best to not kick the can down the road. Is Donnie Murphy worth a 40-man roster spot through the entire winter, into spring training? If he seems to be, and I haven't heard anything negative about his attitude, sign him up. He will be a reliever, or an outfielder, or a catcher that can't be given a major league deal. If he's a guy that -- like a Don Buford in the old day -- figures out hitting late, why not roll with it.
As with the semi-bluff above, there are three valid reasons to keep Murphy. He may, actually, be a MLB-worthy player now. He has a 1.2 WAR in about seven weeks. He can play numerous positions, and has shown more power than expected.
Secondly, if he keeps this trend going into next season, around the trade deadline, he may have value. It's stunning to me to fathom the thought, but consider this: Scott Hairston brought in Ivan Pineyro. If Murphy can flash a 85 or so OPS+ next season, his versatility ought to bring back something of value, if only in a package deal.
If you bring him back for a reasonable amount (I doubt it would be very excessive), and he flails hopelessly in the spring, try to find a trade partner to give a 17-year-old Dominican League arm for him. Or, try to encourage him to go to Iowa again. It worked this season.
I don't have delusions of Murphy being a poor-man's Mark DeRosa. Or anywhere near. That said, if you have talent, you might as well keep it as release it. Conversely, if his season has been a mirage, let him go with a nice recommendation, and consider welcoming him back next year if he starts playing like the Donnie Murphy we remember.
And, yes, the season has reached the point where "keeping Donnie Murphy on the 40-man" is a valid point of discussion. It was that, or go in-depth on Brooks Raley as a LOOGY.