Would the above constitute "telling lies," within the context of bridge?
No. Lies involve a purposeful mental state or intent to mislead those who are expected to rely on your statements. What you describe reflects lack of skill at bridge, whence "lies" is a careless term for criticism of your bids.
Lies have to do with statements of facts which can be objectively verifiable either as true or false. Your bids (what the hypothetical person calls "lies") are not falsehoods, but the product of your subjective (1) assessment [of your cards] and (2) your bidding style. Although your bids may be affected by a lack of skill, they in no way constitute or imply a (true or false) statement of fact. If your bids led your partner to infer that you have certain cards, that is merely a subjective interpretation he made from your subjective assessment.
Can a statement be defamatory if it is damaging “out of context?”
Yes. At the end, I'll outline an exception where saying "he tells lies" could defame a bridge player and can effect harm out of [bridge] context. We need to be mindful, though, that this hypothetical scenario is extreme and only for illustrative purposes.
Suppose a non-bridge player heard this bridge player accuse me of
"telling lies" at the bridge club, without understanding or inquiring
into the context, and I lost business as a result. Would the statement
It depends on what exactly his statements are. When the statement can be reasonably construed as opinion, it is not defamatory. Only false statements of fact (or sufficiently implied falsehoods) may lead to a viable claim of defamation.
Your example "Tom doesn't always have in his hand what he says he has" is rather inconclusive and not derogatory because it merely reflects the nature of the game: As you correctly point out, it is habitual and totally valid for bridge players to engage in "bluffing" as part of their bidding style.
For it to constitute defamation, the statement would have to convey something that tends to injure your reputation. For instance, if the publisher conveyed that you purposefully do things to make your partner lose, then that would be defamatory because it tends to discourage others from associating with you:
(1) others would refuse to be your partner in bridge, for they suspect you'll try to make them lose as well, and/or
(2) they'll think of you as an unethical person who betrays his partners.
The first hypothetical effect tends to impair your opportunities to play bridge in clubs or tournaments. The second hypothetical effect might deter others from doing business with you.